PART IV
AIRCRAFT AND AIR-BORNE WEAPONS

Chapter 1
Early Aircraft Developments

Aerial History Before Kitty Hawk

The development of the automatic machine gun was so far ahead of the rest of the mechanical world that shortly after the turn of the twentieth century, as if by a predetermined agreement, progress in this field of endeavor temporarily ceased. It seemed to be waiting for a companion achievement, the airplane, to join in a combination that would result in man's most devastating instrument of war.

Of all the classes of society, perhaps the highly practical gun designer heaped the most ridicule on the "crackpots" who continually tinkered with horseless carriages and contraptions with wings. During this era some of the world's most skilled mechanics worked on the perfection of weapons, since this work represented a certain means for inventors to be reimbursed financially for their efforts. Having accomplished themselves what heretofore was considered impossible, they very humanly did not credit others with being able to do the same. The ability of man to fly in the air was thought to be hardly more than childish fantasy, but patience and ingenuity were at last making a fact of the unbelievable.

As early as the vision of the wonders of flight itself came premonitions of the inevitable horror that would surely follow the phenomenon. Even the early legends of India contain prophecies that in time there would be built "an aerial chariot with sides of iron and clad with wings which hurled down upon the city missiles that destroyed everything on which they fell."

During and following the ancient and medieval ages, men wrote boldly of flying but did little or no experimenting. Most of their theories during these sterile centuries were naturally based on the flight of birds. Roger Bacon, of gunpowder fame, described in his writings an "instrument to flie withall so that one sitting in the midst of the instrument doe turn an engine by which the wings, being artificially composed, may beat the ayre after the manner of a flying bird." Leonardo da Vinci, another prophet of the future, conceived the parachute, "a domed roof of starched linen, 18 feet wide and 18 feet long," by means of which a man could "throw himself from any great height without fear or danger." Theoretical discussion of flying continued to increase throughout the sixteenth, seventeenth, and eighteenth centuries until at last something practical in the way of flight was attempted.

On 19 September 1783, the Montgolfier brothers of Paris, France, built the first successful hot air balloon. Their gas-filled envelope was sent aloft with a sheep, a rooster, and a duck as passengers before the assembled court of Louis XVI. Three days after all had returned in good shape, a brave individual named Jean François Pilâtre de Rozier became the first human aerial passenger. He had hardly landed safely when M. de Yilette, a representative of the Journal de Paris, went aloft with de Rozier. While the newspapers made much of a Frenchman being the first human being to make an ascent, greatest emphasis was placed in pointing out the advantages the balloon would give to an army on land and to a navy at sea. In short order, books were being hawked on the streets of cities in every land close to France predicting that the French would descend upon them some still night, with troops being transported by noiseless balloons. This psychological scare seemed to excite almost everyone about the possibility of the balloon in warfare except the French, who took it simply as a great national achievement and very little else.

A more important discovery took place across the channel in England in 1810 when Sir George Cayley built the world's first glider. It worked to the extent of successfully carrying a man in the

air. The glider was a brilliant achievement in that it not only lifted a man in free flight and landed without killing the operator, but also laid down the first sound aerodynamic principles upon which heavier-than-air machines are based. For in order to be successful, Cayley had to master many complex problems that worked in direct opposition to each other, such as cross-wind stresses, drag, and the constant pull of gravity. Sir George patiently sought by experience just how things actually worked instead of going by mental calculations that were based for the most part on hypothesis. Like many others before him he died thinking himself a failure, whereas in reality he left a great contribution in his chosen field. He undoubtedly was the pioneer in the study and development of elementary aerodynamics.

Although Cayley proved that a man-carrying heavier-than-air machine could be kept aloft by air currents, practically all effort in this direction was dropped in favor of the balloon, the popularity of which was growing by leaps and bounds. The French Revolution gave it its greatest impetus and its first use as a military device. Scarcely a war followed in which the gas-filled bags did not play a conspicuous part.

In this country a Professor Lowe organized the United States Army's aeronautical corps, which saw much active service during the Civil War. The professor himself logged more than 3,000 ascents in captive balloons, often staying aloft all day to observe movements of the Confederate troops. One of his companions on numerous ascents was a young German military attaché, Col. Ferdinand von Zeppelin, who at the time was serving as an observer for his government. He seemed to be more interested in the possibilities of the balloon in warfare than in the tactics employed by the opposing forces.

Its desperate position in the Franco-Prussian War caused France to authorize the formation by Felix Nadar of the "Ballon Poste" in order to float mail and passengers out of the besieged city of Paris. Later, the entire French Government used this method of escape when it seemed certain the city would be captured.

It was during the blockade of Paris that American citizens were first subjected to antiaircraft fire. W. W. Reynolds, an agent for the Remington Arms Co., and C. W. Way, a New York merchant, were caught in the siege. They persuaded the authorities to build them a balloon, and on 7 October 1870, they ascended, accompanied by two French aeronauts. The basket was heavily loaded, mostly with French gold in payment for armament sold to the Emperor Napoleon, and failed to rise properly. As it drifted low toward the German lines, it was shelled by Prussian artillery, sniped at by infantry and followed by troops of galloping horsemen. After several perilous escapes they were finally blown out of range of their pursuers and landed safely beyond the Prussian lines in a field near Amiens.

With the development of a power source known as the gasoline engine, the construction of balloons made with a longitudinal lattice framework of ribs with a light aluminum skin followed. The name "dirigible" was given to this type of airship. The designers believed the day had at last arrived when a balloon could be guided by an outside power source to and from any destination and not be dependent on changeable currents of air for its motive power.

An airship of this type was devised by the French in 1897 but it was far from successful. Two years later Germany developed the first practical aircraft along these lines. Santos-Dumont, a Brazilian living in France, working on different principles from the German inventor, also succeeded in constructing a successful lighter-than-air ship.

The French Army, however, had other ideas concerning aircraft and paid little attention to the successes of the dirigibles. As early as 1891 it had commissioned Clement Ader, considered the foremost aeronautical enthusiast in France, to build for the army its first military heavier-than-air plane. Ader, an electrical engineer by profession, was closely associated with the development of the telephone in France. In observing the activities of balloons at that time, he thought the nation could best protect herself by the construction of flying machines. After selecting the bat as the best model to imitate, he started to build a craft similar in appearance to this creature, which he called the "Avion." It was provided with a 40 horsepower motor driving 2 propellers.

The whole project was kept in great secrecy.

Ader's Avion, the First Government-Sponsored Flying Machine.

The French Government, considering the Ader Hying machine already an accomplishment, appropriated $100,000 for the founding of an arsenal to construct and subsequently arm a fleet of the planes. The plan proved disastrous to both Ader and his military backers, for on 14 October 1897, after 6 years of hard work, the aircraft was completely wrecked in its initial attempt at flight and the authorities refused to advance any more money for further experiments. No doubt the government was anxious to avoid criticism over its already vast expenditure which had nothing to show for it beyond a totally wrecked aircraft.

Sir Hiram Maxim, who originated the world's first successful automatic machine gun, was approached by the British Government which agreed to finance the building of a flying machine if Maxim would design it. The inventor, never a modest man about his ability in any field, agreed to construct a large aircraft of the multiplane type with a wing spread of 120 feet. He provided it with 2 steam engines, each capable of generating 175 horsepower. The completed assembly weighed 7,000 pounds, but like Ader's plane it too was wrecked in its first attempt to fly and the project was abandoned. The British Government, evidently expecting perfect performance as in the case of Maxim's first model of his machine gun, was disappointed and withdrew its support.

Ader's and Maxim's efforts can best be summed up as serious efforts to fly but with no proved results. However, Maxim did contribute one thing to aviation. He argued successfully that an airplane, because it was intended to fly, did not necessarily have to flap its wings like a bird. As he stated, "If airplanes should be constructed like birds to be more efficient, then by the same token locomotives should be built like horses."

Samuel P. Langley was a great pioneer in American aviation who was continually harassed by bad fortune. This former architect, in association with Charles E. Manly, built several contraptions called "Aerodromes" and while they never managed to fly, present-day authorities have adjudged them magnificent failures. That is, they were of sound construction and as advanced as it was possible to be at the time, especially in respect to motive power.

Langley was fortunate in having the services of Manly, a typical American inventive genius. He had designed gasoline engines, weighing only 125 pounds and capable of developing 52 horsepower, which were far in advance of anything known at the time. One of these engines officially generated 1 horsepower to 2.4 pounds in weight. It was successfully run in spite of the assurances of many eminent engineers and experts that it was impossible for a power plant to be designed under eight pounds per horsepower. The ñve- cylindered liquid-cooled motor ran, in an official test, 10 hours without stopping. This happened during an era when it took practically that much time to get the conventional automobile engine started.

In 1903 the Board of Ordnance and Fortification of the United States Army directed Langley to construct a large model of his Aerodrome and appropriated $50,000 to defray the cost of the experiment. This craft with its 52-horsepower

The Launching of Langley's Aerodrome, 7 October 1903.

engine weighed only 830 pounds. Its dimensions were 48 feet in width and 52 feet in length. Two attempts were made to launch the craft from Langley's houseboat on the Potomac River, near Washington, D. C, on 7 October and again on 8 December 1903. During both efforts, according to witnesses, the Aerodrome became entangled in the launching gear and fell headlong in the Potomac. Following the last attempt, the press ridiculed the whole project so much that Congress refused to vote any more money for the venture. Regardless of its apparent good design, the fact remains that it did not fly and each effort to do so resulted in the complete wreckage of the craft in an inglorious manner. As one of the spectators put it, the Aerodrome "slid into the water like a handful of mortar."

The Wright Brothers and Other Early Pilots

It became the lot of two modest young men, Orville and Wilbur Wright, whose background consisted mainly in the building of bicycles, to fulfill the age-old dream that had bested mankind from the earliest days to the twentieth century. For on 17 December 1903, their "contemptible orange crate," held together with glue and wire and powered by a wheezing 4-cylinder gasoline engine, became air-borne after being launched into a 27-mile wind at Kitty Hawk, N. C. Orville Wright was at the controls through the element of chance, the brothers having tossed a coin as to which one would have the signal honor. Wilbur had won, but the first attempted launching 3 days earlier had been unsuccessful because of a broken guy wire at the time of takeoff, and it was now Orville's turn. This act, like almost all others of world-shaking importance, took place in the humblest of surroundings, as the sand dunes on this bleak shore were hardly an appropriate backdrop for what was destined to become both the wonder and the scourge of civilization.

In a halting erratic flight of 120 feet, aviation, as we know it today, came to life. The 12-second phenomenon was witnessed by five heretofore skeptical local residents and by a confident Wilbur Wright. The watchers were John Ward, a boy of 16, John T. Daniels, W. S. Dough, and A. D. Etheridge, all of the nearby Kill Devil life-saving station; and W. C. Brinkley, a lumber buyer. Three of the five had come only to give help in case of disaster, but all had attended the most astounding event of the twentieth century.

Three other flights were made that day. The final one, with Wilbur piloting, started at 12 noon. The distance covered was 852 feet and the time of flight 59 seconds. Immediately following a successful landing, a sudden gust of wind blew

The First Flight by Man.
The Wright Brothers at Kitty Hawk, 17 December 1903.

the airplane over and damaged it so severely it was never flown again.

The Wright brothers' accomplishment was no accident. Their great advance was not in the building of a superior power plant, as Manly, by every known standard of comparison, had surpassed them in the Langley plane. Rather, the real basis of this success was their brilliant achievement in obtaining balance in flight and control of direction by means of wires which acted as rudders and warped the wings of the biplane in any manner desired.

The inventors had prepared carefully for the eventuality of flight, having taken advantage of what little trustworthy science was known on the subject. They then set about to solve for themselves heretofore unmastered difficulties by dogged persistence and great natural aptitude. For example, in constructing their propellers, they profited from what they considered a mistake in Langley's propeller design, and built a homemade wind tunnel to prove the professor's scientific approach on this feature was wrong.

Likewise they gained much from the earlier glider studies of Sir George Cay ley and the great German experimenter, Lilienthal. They actually built and flew identical gliders in order to see for themselves how these men had arrived at their basic principles of aerodynamics. That they were ever watchful for any possibility of betterment in design can best be judged by Orville Wright's statement that he got the idea of wing warping (a means of lateral control in lieu of ailerons or wing flaps) from twisting the top on a cardboard box when wrapping a package in his bicycle store.

The brothers from the first realized that, if they ever got an airplane into the air, they must learn to control it. "We thought," said Wilbur, "that if some method could be found by which it would be possible to practice by the hour instead of by the second there would be hope of advancing the solution of a very difficult problem."

The Wrights decided that the best way to do this was to find some place where the wind commonly blew at about 20 miles an hour, which they estimated was the best velocity in which to practice. They found such a place at Kitty Hawk in the late summer of 1900.

Using various models of gliders, they observed the effects of speed, lift, and pull in varying positions so that they slowly began to learn exactly what to expect when they first attempted to fly.

They experimented with new shapes of wings and found that, by twisting its surface in conjunction with a pivoting rudder, the glider could be balanced in flight.

When not making glider flights, the Wrights utilized all kinds of wing surface materials in the wind tunnel they had made for themselves. Thousands of tests were conducted in this device, 16 inches square and 6 feet long. During the greater part of 1902 they not only sought to find the most efficient manner in which to construct a propeller, but actually designed and built an engine to drive it.

The first aircraft to be successfully air-borne was a mixture of bicycle manufacturing knowledge with considerable aeronautical experience, plus a large measure of genius. Its total weight, including the pilot, was 750 pounds. The motor was officially rated at 12 horsepower, and carried air-borne 63 pounds of weight per horsepower. It had a maximum motor revolution of 1,020 per minute, while each of the 2 propellers had a revolution of 340 times per minute when in flight.

The event was heralded in the press with banner headlines and the public accepted it with both skepticism and awe. People were hardly able to visualize man flying through the skies when the roads and streets were cluttered by "cranks" trying to nurse the "one-lungers" of their horseless carriages back to life. At the same time many individuals realized the military potentialities of aircraft if refinement did follow and a reliable motor could be made that allowed such a device to be used for these purposes. That is, practically everyone realized this but military men themselves, who seemed very content to tinized nitroglycerin with cellulose to form a progressive burning propellant.

This situation was true in all countries, doubtless as a result of the earlier failures of craft designed by Ader, Maxim, and Langley. Nevertheless, the successful flight of the Wright airplane was destined to affect warfare, and especially machine-gun design, just as much as did Vieille's discovery of smokeless powder by rolling gelatinized nitroglycerin to form a progressive burning propellant.

In 1904 the Wright brothers continued their experiments on Huffman Prairie, near Dayton, Ohio, with a new machine. Over a hundred flights were carried out. In 1905 distances up to 24 miles were covered. In the next 2 years the brothers devoted a great deal of their energies to the construction of new machines and to business negotiations. Still very little attention was attracted to their remarkable flights.

In the fall of 1907 the Aerial Experiment Association was organized by Dr. Alexander Graham Bell, inventor of the telephone. Commencing in 1908, simultaneously with the Wright brothers' activities, the association carried on its experiments, with headquarters at Hammonds-port, N. Y. The organization was composed of Dr. Bell, Glenn H. Curtiss, Thomas E. Selfridge, F. W. Baldwin, and J. A. D. McCurdy, the latter two being Canadians.

The association built a number of machines, the design of each being credited to an individual member. The first plane constructed was the "Red Wing," which covered a distance of 319 feet on 12 March 1908. Selfridge was given credit for its general plan although the test flights were conducted by Baldwin.

On 8 August 1908, Wilbur Wright captured the imagination of Europe when he flew his machine over a race course near Le Mans, France. Actually there had been earlier short flights in Europe. Alberto Santos-Dumont, for instance, had flown his biplane for a distance of 150 feet in October 1906 and made other brief hops the same fall. And in 1907 Henry Farman had piloted a Voisin machine at Issy, France, in a circular flight of 1 kilometer.

At Le Mans, Wright was air-borne for only a minute and forty-seven seconds, but 3 days later he was aloft for 4 minutes, during which time he executed all kinds of maneuvers. On 21 September 1908, he remained in the air for more than an hour and a half, flying a distance officially estimated at 42 miles, and afterwards made many other prolonged flights.

The successes of the Wright brothers started a frantic renewal of effort on the part of European inventors and flying machines were constructed in every major country of Europe. The next 5 years were spent in attempts to create new air records. In the middle of 1909 flights of unusual proportions became an everyday occurrence.

Men like Bleriot, Santos-Dumont, Farman, Latham, and Voisin were among the most prominent to contribute to the rapid growth of aviation. They flew great distances and at unbelievable heights in their rickety contraptions. On 15 July 1909, Bleriot crossed the English Channel from Calais to Dover, a distance of 31 miles, in 37 minutes. He landed in a meadow only a few feet away from the spot where Blanchard and an American doctor, Jeffers, had ascended in their balloon for the first aerial channel crossing 120 years before. On 16 November 1909, Farman covered 134 miles in 4 hours, 17 minutes, and 53 seconds.

An American, Glenn Curtiss, carried away the Gordon Bennett prize when an air show was staged at Rheims, France. He did it in a plane of his own construction that averaged the unheard-of speed of 47 miles per hour over the whole course. Curtiss came back to America and won $10,000 offered by the New York World for the first flight from Albany to New York down the Hudson River. By this time he had invented and patented a system whereby a movable hinged aileron controlled a machine in flight, a feature considered by many to be one of the greatest contributions to aviation.

Beginnings of Military Aviation

In this country Congress, having already sponsored a signal failure, was reluctant to give aid to aviation, but in 1908 the Army did show an interest. In October of that year the first test flight for the United States Army took place at Fort Myer, Va. It reserved the right to pay the designer $25,000 provided the machine met certain specifications, which were incidentally above and beyond anything thought remotely possible. One was that the aircraft's speed must hold a continuous 40 miles per hour and fly a distance of 100 miles. The Wrights were the only applicants to submit a complete machine and fulfill the requirements. In the official test the Wright plane flew slightly faster than the specified speed and covered the maximum distance of its fuel load, a total of 125 miles. The entire trial was conducted without any serious mishap. Specifications for the machine, prepared in the administration of Theodore Roosevelt, father of the modern Navy, gave the United States Army the first airplane ever used for military purposes.

This test, purposely carried out over Washington, D. C, where all could see for themselves, created much more of a sensation than did the Kitty Hawk flight 5 years earlier. In fact the press could hardly find sufficient adjectives to describe this new tool of war. Enthusiasm was dampened greatly a few days later by an untimely and tragic accident when Orville Wright, with Lt. Thomas E. Selfridge as co-pilot, on taking off from Fort Myer entangled his propeller with a guy wire, causing the plane to fall to earth. Selfridge became the first airplane fatality, while Wright was severely injured. The public was brought face to face with the sobering fact that, although flying was at length accomplished, the price for future advancement would have to be paid for in blood by its pioneers.

The year 1909 also marked the beginning of aeronautics in Russia. It was started principally as a sport. A private school, located in Moscow, was operated by a civilian named Maslenicoff. It was soon taken over by the government and known from then on as the Aviation School of the Moscow Imperial Aeronautic Association. Later another school was organized at Odessa, and at each army maneuver held after this, officer graduates were invited to show their piloting skill. Any proved ability was recognized by promotion. The training became so popular with the army that a third government flying school was established at Sebastapol. The honor graduates of the earlier classes of the Imperial School, Captain Ulianin and Lieutenants Rudneff, Piotrovsky and Matsievitch, were placed in charge, after first having been ordered to France to observe the latest techniques in the art of handling planes.

The Russian Army Aviation Force was a part of the Engineering Corps, known as the General Military Technical Department, with headquarters at Petrograd. The Russians have always been air minded and their progress was steady throughout this early development period.

The specifications set by the United States Army in 1908 for testing aircraft formed the standard by which the rest of the military world judged the value of planes until 1910. The French then organized what was called the

French Military Competition, which was originated to further the refinement and betterment of design of airplanes in that country.

The conditions to be met by the competing aircraft and the prizes to be awarded the winners were based on the following requirements:

The airplane and engine must have been constructed in France and be capable of a flight of 180 miles without stop, carrying at the same time 660 pounds above the fuel load; the speed must average a minimum of 37.3 miles per hour; and if this much of the test is completed successfully, then altitude flights must be made during which the machine must rise with a full load to a height of 1,460 feet within 15 minutes of taking off.

The machine turning in the best performance would be bought by the Ministry of War for the sum of 100,000 francs, and the manufacturer given an order for 10 additional machines of identical design at 40,000 francs each. An extra bonus of 500 francs would be allowed for each mile an hour reached above the 37.3 minimum.

The makers of the machines turning in the second and third best performance would receive orders for six and four machines respectively, at the same price. If only one machine came up to specifications, the designers would receive an order for all 20 aircraft.

Encouraged by the monetary inducements offered, 16 French producers designed and constructed special types of airplanes, 34 in number, for trial in the 1911 Military Competition. The final test was over the 496-mile course between Rheims and Amiens. Eight planes passed the test, the winner being a pilot named Weyman, flying a Nieuport monoplane with a Gnôme motor. He had an average speed of 73 miles per hour.

This unique plan to give an incentive to aircraft development proved the most beneficial thing that could be done for aviation and, as it turned out, was the salvation of France. The French proceeded from this point to outstrip the world in aircraft design, especially with respect to military types, which were tried as an aid to scouting during army maneuvers. Trials under field conditions showed the officers the minimum amount of service that a plane could contribute while still being of value to the ground forces, and the requirements that would have to be met by an airplane in order to be suitable for general military work.

France's great strides forward in aeronautics were watched closely by her old enemy, Germany. When it became apparent that the French were leaving everyone else far behind in this field, the Kaiser, on 27 January 1912, offered a prize of 50,000 marks as an incentive to improve aviation for German military use. The contest was to be arranged and awards made by members of the Imperial Automobile Club, Imperial Aero Club, members of the German Automobile Constructors' Association, and delegates of the Navy and War Departments.

This gesture from the Kaiser was the signal for the German nation to concentrate on aviation. The Aerial League of Germany started a public subscription which brought in 7,234,506 marks the first year. The plan of the league was to train the largest number of pilots in the shortest time in order to form an adequate reserve, thus encouraging civilian interest in the scheme. Its success was out of the ordinary; by the end of 1912, 230 military pilots were registered and by the next year 600 were graduated. The number of builders grew from 20 in 1912 to 50 the following year. These successes of the Aerial League were instrumental in causing the Reichstag to pass a bill authorizing 35,000,000 marks for military aeronautics for the next 5 years.

This was all that was needed to bring German aviation to a point of efficiency where record after record began to fall. The year 1913 saw the endurance mark raised by Reinhold Boehm to 24 hours and 12 minutes, and an altitude figure set by Heinrich Oelrich at 26,246 feet. In this one year over a hundred other records were established. For instance, an aviator named Landsmann covered 1,335 miles in a single flight which was at the time the longest distance ever traveled by man in one day. The secret of the plane lay in the design of its Mercedes motor, which was a direct result of the interest created by the Kaiser's award to encourage inventors.

After the accident that cost the life of Lieutenant Selfridge, there was a stalemate in American military aviation. The next official flight took place at Fort Myer again, although not until

July 1909. The machine, which was another Wright, successfully passed the tests and was bought by the Government. Lts. Frank P. Lahm and Benjamin D. Foulois were assigned to receive flying lessons from the Wrights. An aviation field was established at College Park, Md., and a young captain, Charles DeForest Chandler, then disbursing officer of the Signal Corps, was made officer in charge of the Aeronautics Division of the Signal Corps.

Wilbur Wright served as the instructor and taught Captain Chandler and Lts. F. P. Lahm, Benjamin D. Foulois, Frederick E. Humphreys, T. DeWitt Milling, H. H. Arnold, and George C. Sweet, the latter being assigned to the school for instruction by the Navy Department.

The next venture by the Army in aviation was the acceptance of its first dirigible in October 1909. It was commanded by Capt. Thomas G. Baldwin. It too was initially tested at Fort Myer, with Lieutenant Lahm in charge. After successfully meeting all requirements, it was flown to Omaha and turned over to Lts. R. S. Bamberger and John G. Winter, both of the Cavalry.

These developments were followed by the failure of Congress to allow adequate appropriations for aviation. Again things came to a standstill as far as the Army was concerned through 1910-11,

One of the Airplanes Used by the Constitucionalistas in Mexico to Bomb Federal Gun Boats.

while officers of the newly formed Army Aeronautics Division attended voluntarily nonmilitary aviation meets and followed the literature on the work done by civilian enthusiasts.

European countries were in the midst of preparing for the day when airplanes would be used in conflict, but to Mexico goes the distinction of being the first country to employ aircraft in warfare. During the Constitucionalista campaigns against the Diaz regime in late 1910, a conglomerate assortment of aircraft was purchased from civilian builders in the United States and American aviators employed to fly the planes. In spite of the questionable quality of the flying matériel that was assembled and the still more dubious military value of the aerial maneuvers, this small flying force did do patrol and reconnaissance work, particularly in locating guerrilla troops in their mountain retreats. With the victory of the Constitucionalista regime, the American professionals were released and the Flying Corps of the Republic of Mexico formed.

During the Mexican border incident of 1911 the United States Army found itself without a single plane to send to the troops in the field. This greatly agitated the few aeronautically minded officers who were in the service, as they could see that any good work done at this time by a flying machine would be invaluable in future planning and a wonderful incentive for asking Congress to appropriate desperately needed funds.

With air development left in the hands of civilians and with military authorities still taking a dim view of the role aircraft could play in warfare, by an odd quirk of fate the United States was still the first government to use an airplane under conditions that approximated war between major powers. The border incident with Mexico was a logical opportunity for this to occur and the ever-alert civilian promoters did not let it go unheeded. A Wright flying machine, the personal property of Mr. Robert J. Collier, president of the Aero Club of America, was loaned to the United States Government for use on the border. With this machine Lt. B. D. Foulois and a civilian, Mr. P. O. Parmalee, made a number of flights along the border carrying messages between officers in command.

Pioneer Attempts at Aerial Armament

Civilian enthusiasts in the United States were aware of the fact that without Government backing they could never progress beyond the novelty stage of flying. They continuously planned events calculated to impress or at least interest the military high command. This was often done with the aid of aeronautically minded Army personnel who willingly donated their services whenever possible to further the cause.

One of the most colorful of these demonstrations, which was to have a far reaching effect, was carried out before a crowd at Sheepshead Bay race track on Long Island, N. Y. in August 1910. A pusher plane piloted by Glenn Curtiss, an aviation pioneer second only to the Wrights, also carried 27-year-old Second Lt. Jacob E. Fickel, who had won a reputation as an expert marksman in his 3 years of military service since enlisting as a private.

All afternoon the tense crowd had been watching the antics of the flimsily constructed flying machines. The spectators had been promised an act that had never before been attempted, and they waited patiently as the young soldier climbed aboard carrying with him a regulation caliber .30 Springfield infantry rifle.

Lieutenant Fickel's intention was to fire the first shot from an airplane in flight at a target on the ground. Because of his proved marksmanship he was chosen to perform in the opening act of a drama the final outcome of which no one can even imagine.

With Curtiss at the controls and Fickel clutching the rifle with one hand and a wing strut with the other, the plane took off. After gaining an altitude of 300 feet it circled the target that had been erected in the center field of the race track. Four times the young officer, when he was not clinging for dear life, took aim and fired. Two of his four shots were bull's-eyes. The startled crowd roared its admiration of his skill and at the same time must have sensed the beginning of things certain to follow.

At the time just to keep a machine air-borne was a feat in itself, but to possess also the power to bring an adversary to earth stimulated the imagination, and the press made the most of it. Soldiers were pictured being transported by

The First Shot Fired from an Airplane. Glenn Curtiss, Pilot, and 2nd Lt. Jacob E. Fickel Holding the Rifle.

planes or silent gliders and noiseless invisible wars were predicted by the use of smokeless powder and rifle-muffling devices. The impact on the public was terrific, but military minds remained skeptical. They mustered mathematical calculations to prove that nothing but a rifle could be fired from a plane, one shot at a time, and under certain conditions only since successive and rapid explosions would upset the plane. And under no conditions could any great weight be dropped in flight since its sudden release would be certain to make the plane fall out of control.

The development of speedy aircraft was also discounted by the "experts" as being wholly unnecessary as far as their use for war was concerned. Those who expressed the possibility of equipping airplanes with two motors were laughed at loudly. A principle of aerodynamics was claimed that, if two engines were mounted, one would exert a mere fraction of its power due to its proximity to the other. It was happily concluded that no single engine could possibly lift the additional one, and that, in case such an impossibility was accomplished, failure of one motor would force the plane into a power-driven spin. But these theories and calculations soon went the way of most expert advice from people who have been educated beyond their own capacity for intelligence.

On 14 November 1910, a Curtiss plane piloted by Lt. Eugene Ely took off from the United States cruiser Birmingham and on 18 January 1911, another Curtiss plane, also piloted by Lieutenant Ely, landed on the quarter deck of the armored cruiser Pennsylvania, anchored in San Francisco Bay. A crude arresting gear, with hooks fastened on the under carriage of the plane

and an ingenious arrangement of ropes attached to sand bags stretched across the wooden deck, brought the machine to a stop within 30 feet after landing. A half hour later the pilot raced his machine down the boarded landing strip and became air-borne before reaching the edge of the deck.

This was the first step to adapt aircraft to naval use. A week later, on 26 January 1911, Glenn Curtiss, after one unsuccessful attempt to make a hydroplane out of his machine, the "June Bug," put floats under another plane and took off after a short run. A Frenchman, Henri Fabre, on 28 March 1910, had previously arisen from the water and flown about 1,000 feet but was completely wrecked in trying to land. Curtiss made the first successful take off and landing.

On 17 February 1911, Curtiss made another advance in naval aviation, for on that date he flew his pontoon-equipped aircraft alongside the Pennsylvania in the harbor at San Diego, Calif., and was hoisted aboard with the ship's crane. After a short stay aboard the vessel, the machine was lilted over the side and Curtiss flew it back to its hangar on North Island. The system of hoisting a seaplane on board and putting it over the side with a crane is still followed by British battleships and cruisers.

While development in land planes was unquestionably greater in several other nations, the American Navy was making her bid for world supremacy in naval aviation. An aeronautical school was established on the academy grounds at Annapolis, Md. The study of getting an aircraft into flight from a battleship's deck was the first major problem taken up at the school.

It was the opinion of United States naval architects that a more practical method of launching an aircraft than putting it over the side was needed if the airplane itself was to play a dominant role in future wars. The daily papers, approximately 18 months after Curtiss made his novel experiment, announced the successful test of a launcher for catapulting planes from the deck of a ship. The device was constructed at the Navy Yard, Washington, D. C, and a successful trial was held there on 12 November 1912. Naval authorities announced through the

The Successful Trial of the Chamblis Catapult at the Washington Navy Yard, 12 November 1912.

press that the device would make possible the use of older and outmoded ships as floating hangars and launching platforms. Planes from these vessels could be used profitably in conjunction with the main fighting units of the fleet for scouting and spotting work.

Navy mathematicians also brought out the startling information that if an aircraft so used could maintain a speed of 47.4 miles per hour it was absolutely safe from enemy antiaircraft fire. Such phenomenal speed would at the same time render the craft useless for anything other than close observation work. No rifleman in the aircraft, they said, could possibly hit anything from an object moving at such a rate, and, as they further pointed out, any sudden release of a heavy object would be certain to upset the plane. Dropping a bomb was thus out of the question, and as there was no possibility of damaging a battleship, the airplane in warfare seemed to qualify only as a harmless nuisance.

The Italians were the first to destroy the myth that heavy bombs could not be dropped. During the Italian-Turkish War of 1911, they not only used heavier-than-air ships-initially in actual warfare between major powers, but also were the first to drop bombs on an enemy. Previously, Lt. Myron S. Crissy, United States Army, in January 1911, had dropped a small bomb in San Francisco Bay, and gained the distinction of dropping the first such projectile from the air. His pilot was a civilian, P. O. Parmalee.

Italy had already made secret tests to determine the effect on airplanes of releasing heavy objects while in flight. Capt. Alessandro Guidoni of the Royal Italian Navy, considered in his country a leading authority on aerodynamics, was in charge. The plane used was an English-built Farman capable of lifting torpedoes weighing 700 pounds. Captain Guidoni became so efficient in this type of launching that he is recorded as making 9 direct hits out of 10 tries on a target a mile and a half distant. He exploded the accepted theory that a plane is upset by the sudden release of a heavy object in describing his plane's reaction during the successful torpedo droppings.

"When the motion forward is uniform, there is a dynamic equilibrium between the different forces. As soon as the launching has taken place, two resultants will act upon the plane, one vertical due to the difference between the lift and the weight and one horizontal due to the difference between the thrust and head resistance.

"Owing to these two forces the plane acquires two corresponding accelerations until the dynamic equilibrium is regained, the vertical acceleration giving a rising motion to the machine. Thus there always exists an equilibrium between the applied force when the forces of inertia and the resistance meet in the ascending motion."

The Italians first put this information into application by dropping sizable bombs on the Turks. The damage was slight because of the fact that no sight other than the aviator's guess was employed in putting the bombs on the target. The event contributed nothing other than a glimpse of the kind of warfare that was to follow.

The year 1912 in the United States found our Army interested in establishing aviation in the Philippines. Lt. Frank P. Lahm, with a single Wright plane, was sent to the islands for the purpose of establishing a flying school. This was again followed by a lack of congressional appropriations and even such meager plans were prevented from being put into effect. What a few years before promised to be the nucleus of an air force had by now practically ceased to exist.

Finally on 24 August 1912, Congress did appropriate $100,000 for the purchase, maintenance, and operation of Army aircraft. Twelve planes were contracted for in that year, and Maj. Samuel Reber was put in charge of the so-called Aeronautics Division. The appointment came close to being an empty honor. When an inventory was taken nearly a year later in June 1913, it showed the exact distribution of machines and pilots to be: Texas City, Tex., 11 pilots, 6 training machines and 4 suitable for military use; North Island, San Diego, Calif., 5 pilots, 1 training plane, and 1 military plane; Philippine Islands, 1 pilot, 1 training plane and no plane suitable for military use. The general equipment of this handful of aviators consisted of the barest necessities, as the allowance made by Congress was too slight to afford more than the most necessary spare parts, with a few tents to house both materiel and men.

The next fiscal year's appropriation was scarcely better, being only $125,000. This made

it impossible to acquire the motor trucks, repair shops, extra motors, and other equipment considered absolutely vital.

With so little money the Signal Corps was unable to extend the aviation branch beyond a mere hand-to-mouth existence. Progress in this branch of the service naturally ceased, although it was able to muster two machines and five pilots for the war maneuvers held in Connecticut beginning 24 August 1912. This represented the first official use of aircraft on United States Army maneuvers. The pilots were Capt. F. B. Hennessy, and Lts. B. D. Foulois, Harold Geiger, T. DeWitt Milling, and Harry Graham.

Lieutenants Milling and Geiger barely averted a serious accident when their plane was slow to get airborne after take-off with the wind, and missed a head-on collision with a stone wall by inches. An alert Signal Corps cameraman recorded the incident for posterity. An investigation later proved the near accident was due to the manner in which Army engineers had built the field. The only way pilots could take off was to the north, since the south end came to an abrupt end flush with a forest of tall trees. Unfortunately the prevailing winds were such as to be always behind the craft. The Army learned from this experience that air fields had to be constructed with the winds taken into consideration.

The British Admiralty, which must have known about the successful dropping of aerial torpedoes by Italy, did not accept completely the American Navy's theory that the battleship could not be harmed by the airplane. In order to come to a definite conclusion, the British built at Hen-don, England, a mock battleship and then bombed it with exact duplicates of the Italian high explosive and incendiary bombs. The latter did the most damage to the dummy vessel. The report on the incident shows more than anything else the size and over-all damage potentialities of the bombs.

"The harm done by bombs dropped from airplanes on battleships is still little more than a theory. There are some who think the battleship still adequately protected from aerial bombs, but we must not take for granted that aerial bombs will never be made heavier than 10 or 15 pounds, and an airplane will never be able to drop a weight heavy enough to harm a battleship without losing its control. Actual experiments have shown that such a weight up to 175 pounds can be dropped without the plane being thrown out of control, and, needless to say, a bomb or a similar load of explosives from 26 to 100 pounds can do harm to the most heavily armored battleship."

A Curtiss Airplane, the First to Accompany the Army in Maneuvers, Clearing a Stone Wall.

This report showed for one thing that the British, aware of both the Italian weight dropping and the contradictory theory of the Americans, were still as confused at the end of the experiment as they were at its beginning.

College Park, Md., had become the United States Army's chief aeronautical experiment station. When the possibility of bombing became an accepted fact, it was approached from the typical American viewpoint. What good was the dropping of high explosives unless they could be placed where they would do the desired damage? First Lt. R. E. Scott, U. S. Coast Artillery, was ingenious enough to find a workable solution to the problem. For he originated a device that could be aimed at the target. It made a simple computation whereby speed, drift, and time of fall were calculated and the world's first practical bombsight came into being. What is now known as the timing-sight principle was used.

As early as October 1911, Scott made experimental bomb droppings from an airplane at College Park, piloted by Lt. T. DeWitt Milling. Scott simplified the problem of air bombing by combining a gunner's quadrant, a telescope, and a stop watch. With this device he could determine ground speed quickly and with the known altitude, transpose from a set of tables the proper angle at which to aim the telescope. The bomb was released when the target appeared in the sight and reasonable accuracy was assured.

The telescope was mounted on gimbals and could be pivoted along the graduated arc from vertical to a horizontal position. To operate the bombsight, Scott, when approaching the target at a known altitude, read from a barometer, would first find his ground speed. He did this by setting the telescope at 45° and sighting an object. The telescope was then swung to the vertical position and the stop watch clocked the time interval necessary for the object to reappear. With this information he would read from a chart the proper angular setting of the telescope to hit the target. When the target then passed in view, the bomb was released.

From the experience of hundreds of drops, Scott made himself a set of prepared tables that took in practically every speed and height that were commonly used and accepted in bombing tests. The most difficult was the obtaining of accurate data from which he could compute the angular table for determining the exact instant of drop.

Following these experiments, Army aviators who witnessed them agreed that the device was a complete success, and that only target practice was needed. It was also decided that the pilot's skill would play no small part in the successful hitting of targets and that a reasonable degree of accuracy could be obtained from altitudes exceeding 3,000 feet. Below this height it was not thought that an airplane would be sufficiently immune from hostile fire to warrant its use.

When this practical sighting system had been developed, the Army found that further trials were not possible on its small appropriations and all experiments were ordered discontinued. Scott, being very disappointed at this turn of events, carried his sight abroad where it aroused great interest. He entered the Michelin competition held in France, which offered as much as $30,000 in prizes for the best bomb drop on a target 20 meters in diameter at various altitudes from 200 to 1,000 meters. Scott won first prize at the 200-meters altitude by placing his bomb within 1½ meters of the target center. He hit in the target at every height up to 1,000 meters.

Scott was faced with the decision many other American inventors before him were forced to consider. He realized that inducements abroad were such as to preclude wasting his time on further developments of a device that was not wanted at home. Patriotism alone could not contribute sufficient material inducement for staying in the service of his own government and he reluctantly resigned his commission to exploit his invention overseas.

The Navy at its aviation station at Annapolis also made a great contribution to flying at this time. On 26 July 1912, the first wireless message ever sent from an aircraft was transmitted from a hydroplane to the United States torpedo boat Stringham. The message, radiocast by Ensign Charles Hamilton Maddox from a height of 300 feet and a distance of 1 mile, consisted of, "We are off the water, going ahead full speed on course for Naval Academy."

The entire apparatus was designed by Maddox and had many new improvements over previous

unsuccessful experiments. Besides making it much lighter, a few other features were added that included a new type of aerial and a shielding device that overcame the noise of the engine. The achievement was truly remarkable as the lifting capacity of hydroplanes was so limited it was thought to be impossible to design a light enough sending set capable of transmission.

This weight factor was so critical that the Army was searching for a substitute for radio, then being used universally on land. The efforts to develop another means of aircraft communication resulted in consideration and testing of a device that today can hardly be taken seriously.

This gadget was known as the Means Smoke Telegraph System. The signal apparatus, fastened on the leading edge on the upper wing of the plane, was first tried out at Signal Corps Aviation Field in College Park. A trigger arrangement was located beside the pilot who could control the length of time for opening a valve that allowed dense smoke to be expelled. The aviator could then fly along puffing out dots and dashes, a long puff for the dash and a ball of smoke for the dot. Much publicity was given the contrivance by the promoter and even the conservative Literary Digest predicted that bulky wireless instruments, and perhaps even the conventional telegraph, were doomed by this clever machine.

It may be true that the Army's test of the Means smoke telegraph today has a humorous angle, but most certainly the next experiment successfully carried out by the Army at its College Park flying field has proved anything but funny. From the day of its conception it has presented to every nation on earth one of the most serious problems to confront it. For the combination of machine-gun fire with mobility of aircraft then made its first appearance.

Chapter 2
Lewis Aircraft Machine Gun

The First Aerial Machine Gun

A week after the world was saddened by news of Wilbur Wright's death from typhoid fever on Memorial Day, 1912, an event concerning aviation took place on 7 June 1912, that would in time directly affect mankind far more than did the pioneer flight at Kitty Hawk. For on this day, Capt. Charles DeForest Chandler successfully fired a full automatic weapon from an aircraft in flight for the first time in aviation history.

The experiment was carried out unofficially. Lt. Col. Isaac N. Lewis, Coast Artillery, United States Army, had devised a weapon for the Automatic Arms Co. of Buffalo, N. Y. Feeling it was a most progressive step in machine-gun construction, he visualized its use in the most promising development of the day, the flying machine. With this in mind and knowing that success of his experiment would guarantee endless favorable publicity, he arrived at College Park with no introduction other than his rank. The suggestion that the weapon be air fired as an incentive both to aviation and machine-gun development was placed before Captain Chandler, the commanding officer at College Park. The latter not only granted the request but offered to fire it personally.

This early model of the Lewis air-cooled automatic machine gun weighed 25 pounds, 6 ounces, and was chambered for the caliber .30/06 United States Army infantry rifle cartridge. The ammunition was contained in a circular drum that slipped over a post on top of the receiver. The rate of fire of the weapon was given as well above 750 rounds per minute. For this trial, however, it was slowed down by putting unusual tension on the return spring. Lewis thought the best rate for the occasion to be 500 shots a minute, allowing the gunner to empty the drum in 6 seconds. The gun had no sighting arrangement other than looking along the top of the unusually large aluminum barrel jacket.

Chandler, after being shown by Lewis how to operate the weapon and being made familiar with the kick and amount of jump when operating it full automatic, took his place in the Type

Lt. Col. Isaac N. Lewis, U.S.A.

B Wright pusher plane with the muzzle of the gun resting on the cross bar upon which pilot and observer placed their feet. It had been agreed that the firing was to take place a short distance in front of the hangar. In the interest of safety a decision was made to fly at a low altitude.

A target, consisting of a piece of cheesecloth 6 by 7 feet in size, was laid on the ground. Lewis calculated that the plane would travel over the length of the target in one-tenth of a second. Lt. T. DeWitt Milling, who was piloting the plane, made three approaches at an altitude of 250 feet. Each time a short burst was fired. Examination showed five hits on the target and several bullet holes directly in front of the cheesecloth. Chandler could not see where the bullets were hitting on the ground and when circling over some adjacent fish ponds, he fired the remainder of the drum into the water to observe the spacing of the bullets by the splashes.

This unscheduled burst caused the colonel much concern. Thinking that Chandler may have fired the weapon accidentally, he asked the observers to take cover in the hangars as a precautionary measure. He concluded that if the trigger had been pulled once accidentally, it might be done again. Later Lewis was much relieved by the captain's explanation for firing into the pond.

Realizing they had contributed to aviation history, they jubilantly planned another trial the following day. This time a target 2 yards wide and 18 yards in length was used, and again the 2 officers, Chandler and Milling, took off. From experience gained the day before, they decided to raise the altitude to 550 feet. Even at the increased height, 14 shots out of 44 fired hit the target, and the remainder of the bullets left holes in the ground close by. As the limited space allowed the gunner practically no traverse, accuracy depended much on steering the machine steadily over the target.

For once the newspapers were caught by surprise and although the firing was done almost within sight of the Nation's capitol, the news did not reach the public until the following day. Had it not been for an enthusiastic amateur photographer named MacCartee, who journeyed to College Park and asked Captain Chandler to pose with the gun in the plane, no picture of the event would be in existence today. At the time. Lieutenant Milling was away on duty and Lieutenant Kirkland had to "stand in" as the pilot when the picture was being made.

Newspapers and magazines everywhere carried the picture and much was written about the future of aircraft in warfare. The experiment proved that sustained fire would not upset a plane's balance, as the experts had accepted as a certainty. In accordance with a customary journalistic privilege, reporters assigned to the War Department used the incident to interview a spokesman of the General Staff. They came away with a very clear understanding from the high command that aircraft were suitable for scouting only. Any dream of aerial conflict was simply the product of a too fertile imagination, a failing often found in younger men with insufficient service to recognize certain things as utterly absurd. Besides the experiment had been run without official sanction, which, as far as the military authorities were concerned, left it in the category of having never happened.

There is no desire at this point to take advantage of the hindsight that the passage of time affords. The limited flying and erratic performance of aircraft in the United States had impressed officials only with their possibilities for scouting and message carrying. On the other hand, officers, mentally capable of mastering the problems of staying aloft with their intricate machines, were also the type who had not only vision but the means of extending it to reality. Even so, it was extremely doubtful if a single officer at College Park at the time could foresee the mighty surge of aircraft armament development that was to occur in the next 5 years, particularly in Europe where war was only months away.

If the high military authorities had any idea of dampening Lewis's enthusiasm for the potential uses of his machine gun in aircraft, they certainly overlooked his reputation. The colonel was a man who did not discourage easily. When dedicating himself to a purpose, he was no respecter of person, rank, or position in life, and he had already acquired the title, "the stormy petrel of the service." Having been a successful inventor throughout his military career, he had the utmost contempt for those who could not see the

Captain Chandler, the First Man to Fire a Machine Gun from the Air, with Lt. Kirkland, His Pilot, at College Park, Maryland.

obvious possibilities of anything that had required so much of his time and labor to conceive and construct.

Early Development of the Lewis Gun

Isaac Newton Lewis was born at New Salem, Pa., on 12 October 1858, and was taken west by his parents while he was still a child. He was appointed to the United States Military Academy from Kansas in 1880 when 21 years of age. He graduated eleventh in a class of 37 in 1884, and was commissioned a second lieutenant in the Coast Artillery. From 1894 to 1898 he was a member of the board on regulation of Coast Artillery fire in New York Harbor. In 1898 he became recorder of the Board of Ordnance and Fortification of Washington, D. C, and the following year made a study of weapons in Europe. This led to the reorganization and rearmament of our field artillery. He later invented a number of rangefinders and mechanical and electric instruments used for controlling artillery fire. From 1904 to 1911 he was instructor and director of the Coast Artillery School at Fortress Monroe, Va., and rose to the rank of lieutenant colonel.

In the early part of 1910 Lewis was approached by officials of the Automatic Arms Co., Buffalo, N. Y., in relation to assigning him substantial stock in the company if he would produce a machine gun based either on patents they already owned or on anything he cared to originate. He agreed to the proposal and joined the firm. This business union resulted in his devising an air-cooled machine gun. In 1911 when the prototype reached a stage he felt was advanced enough to be exhibited, he brought a handmade model to Washington, D. C., and showed it to Maj. Gen. Leonard Wood, then Army Chief of Staff.

A short time later Lewis made four more guns patterned after the prototype he had shown the Army Chief of Staff. These weapons were also presented in person to the Secretary of War and other high ranking Army officers. He fired them many times before these dignitaries on the Fort Myer rifle range and, while in no ways was it an official test, many were distinctly impressed. The guns were chambered for the standard United States infantry rifle cartridge caliber .30/06.

After the College Park demonstration of aerial firing, the weapons were formally presented to the Board of Ordnance and Fortifications for consideration. When no definite decision was reached by the Board, Lewis became annoyed by what he called "a strictly negative attitude," and like practically all successful machine-gun inventors before him, he turned to Europe for a ready market and appreciation of his effort. He asked for leave of absence and in January 1913 sailed to Liege, Belgium, taking with him the four guns manufactured originally for testing by the United States Army.

These weapons were exhibited in various countries in Europe and resulted in the

Lewis Machine Gun, Cal. .303, British.

formation in Liége of a company known as the "Armes Automatiques Lewis." While manufacture was originally centered at Liége, the whole program was later removed to the British Small Arms Co., of Birmingham, England, which at the time was the world's largest producer of small arms. Its officials, after having seen the demonstration of the Lewis gun and the enthusiasm of the generally conservative British officers, immediately offered to erect necessary buildings and take over large-scale fabrication of the weapons. The proposal was agreeable to the president and stockholders of the Automatic Arms Co., who did everything possible to help the English company to attain mass production of the lightweight automatic weapon.

Just as Maxim was the first to introduce the full automatic gun, so Lewis was the father of the lightweight automatic machine gun. Its weight and self-contained feed system holding 47 or 96 cartridges without use of links or belting made it possible for one man to represent the threat formerly offered by a three- or four-man machine-gun crew.

Without detracting from the skill Colonel Lewis showed in assembling one of the lightest and most reliable firing mechanisms ever devised, it must be remembered that the basic operating principles were already the property of the Automatic Arms Co. before Lewis became a member of the firm in late 1910. At the time of the firm's organization Samuel Neal McClean assigned to it all patent rights to his machine gun, better known as the McClean-Lissak automatic rifle. The producers of the weapon made several unsuccessful attempts to interest the Government in it but McClean, like many other inventors, could not leave well enough alone. Having the basic principles for a reliable automatic machine gun, he added various other gadgets until the assembly was so overburdened it lost practically all value as a compact and efficient military weapon.

Lewis deserves full credit for concentrating on the problem at hand and refining the original idea down to the barest necessities that would permit reliable operation, especially for lengthy bursts. The McClean gun was originally made to use both water and air cooling and to be tripod mounted. The gun could also be detached for shoulder firing. This intended all-purpose weapon, as is usually the case, was too bulky for any specified purpose.

Lewis's own originality and inventive ability were displayed when he overcame obstacles in the difficult task of improvement. His solutions to the various problems were patented and assigned to the Automatic Arms Co. Among the most notable innovations were the cooling jacket, the clock-type spring and the rate-of-fire regulator. The finished weapon is rightfully called the Lewis gun, as the colonel redesigned, assembled, refined, and, in some features, created an automatic machine gun that soon became the most discussed instrument of war of its day.

After 25 years of active duty in the Coast Artillery, Lewis retired in order to be able to devote his entire time to further improvement and promotion of his gun. When he left, he held the rank of colonel.

The Lewis Gun in World War I

A Serbian student named Princip, armed with an American-designed auto-loading pistol, on 28 June 1914, assassinated Archduke Francis Ferdinand of Austria to start what might well be called the First Great Machine Gun War. The automatic weapon had heretofore been employed only in minor conflicts, which had served to show its potentialities. In the 1914-18 war it was estimated that 92 percent of all casualties were inflicted with this highly lethal type of weapon.

After the declaration of war, the entire capacity of the Birmingham Small Arms Co. was turned over to the production of Lewis guns. It was estimated by the manufacturers that six Lewis guns could be made to one Maxim-Vickers. Lewis must be credited with knowing the value of being able to produce a weapon quickly in an emergency. To this end he worked diligently, simplifying all components that required skill above normal to fabricate.

The demand of the British and Belgians for Lewis guns was so great that their factories could not begin to keep pace with the use, and the Savage Arms Corp., of Utica, N. Y., was contracted with to make the weapons in the United States. The Savage Co. was organized in 1894 to manufacture a hammerless repeating high-power

Section Drawing of Lewis Machine Gun.

rifle invented by Arthur Savage, a rifle designer far in advance of his time. By 1915 it was manufacturing, in addition to high-power rifles and ammunition, several .22 caliber rifles and an automatic pistol. In that year the corporation was merged with the Driggs-Seabury Ordnance Co., which held a number of basic patents on automatic arms.

In 2 years, this plant reached an output of 400 Lewis guns per week. After production was well under way and thousands had been delivered, the Lewis was adopted by the British as its first-line light machine gun. By that time all modifications were established and the weapon was made without any basic changes throughout the war.

The action of the weapon is quite simple. The locking of the breech depends upon the semicircular movement of locking lugs at the rear of a rotating bolt, a principle first used by the Mannlicher straight-pull rifle and later by the Schmidt-Rubin. The striker is located on a post fixed at the rear of the gas piston and reciprocates in a helical slot cut in the bolt body.

When the piston is engaged by a sear, the bolt is held retracted in what is known as the cocked bolt position. Upon its release by pulling rearward on the trigger, the piston and bolt are driven forward by the stored energy of the clock-type return spring. The face of the bolt shoves the already indexed cartridge ahead of it into the chamber.

At this point the striker post is held securely in a recess at the rear of the bolt slot, with its left side bearing against an inner portion of the curved part of the slot. The locking lugs on the bolt engage with the guide grooves on the action body and prevent the bolt from being rotated until such time as the lugs are opposite their locking recesses. The continued forward motion of the striker post along the curved portion of its slot rotates the bolt body and lugs in their recesses, while the striker continues on along a straight path in the slot until its point smashes into the primer of the chambered cartridge.

The barrel, bolt, and piston are all securely locked until the bullet has passed an orifice in the barrel at which point gas is bled into a cylinder and force brought to bear on the head of the gas piston. By the time the action begins a rearward movement, the bullet has safely cleared the bore and the gas piston is then suddenly thrust back with great force.

This movement of the piston withdraws the striker and next the rotation of the bolt unlocks the action. The extractor holding to the base of the cartridge then withdraws it from the chamber and a pivoting ejector knocks the empty case to the ground. The continued action rearward of the gas piston actuates the circular drum type feeder, by means of a lug, causing it to rotate a fraction of a revolution and index the incoming round in position to be picked up by the bolt for chambering.

Some of the distinctive features of the weapon are the positive safeguard against firing until the bolt is securely locked, and the design of the return spring mechanism. The latter consists of a clock-type spring mounted inside a pinion which engages a rack on the under side of the gas piston. The entire spring mechanism is mounted in a casing on the pistol grip unit. The advantages of this simple and ingenious arrangement are many. The easily accessible spring is located out of the way of the reciprocating parts. It is practically impossible to get dirt and other foreign matter into its housing. The whole unit can be removed in a matter of seconds along with the trigger assembly, also located on the pistol grip. Any desired amount of tension can be attained without stopping the gun, as the clocklike spring can be wound externally until the desired result is reached. This permits to a limited degree the control of rate of fire. The trigger assembly also has a very simple design with very low inertia. An unusual feature is that no provision is made for firing single shots, the weapon being designed for full automatic only.

Another radical departure from conventional machine-gun design is the unique feed system. Although Maxim in 1889 successfully used such a cartridge container and the American Government likewise had tested the Carr gun with a similar flat rotating drum feed, it remained for Lewis to lighten it by practical design. By using a reasonable cartridge content of 47 for ground use and 96 for air, both weight and profile are held to a minimum. The Carr drum held as many

Lewis Aircraft Machine Gun, Model 1914, Cal. .303, British.

as 305 rounds, which made the gun too clumsy and breech heavy to be handled without tripod.

The standard Lewis drum holds 47 rounds in two circular rows and is fastened horizontally by a clip to a top post located to the rear in line with the chamber. During operation the drum is rotated counterclockwise by a ratchet pawl working off the reciprocating piston body. It can be exchanged in a few seconds, in fact so fast that only a slight pause in a long burst is apparent, since belt or links are not required and firing is generally interrupted anyway after 50 shots. This is one of the weapon's many desirable features for military service.

The British made a slight change in the gun by using a closer-fitting metal tube of aluminum in place of the conventional radiator in order to lighten the weapon for aircraft use. This model was employed in the first aerial firing of a machine gun in England. (A similar exhibition, made by Belgian pilots with the Lewis gun at the Brasschaet Military Aeronautics Grounds in Belgium in December 1912, was the first official demonstration of its kind in Europe.) The British plane, a Graham White biplane, was piloted by Marcus D. Manton, a civilian, and the demonstration took place above the Bisley airfield on 27 November 1913. A machine gunner, from an improvised platform located between the pilot and the landing gear, fired repeated bursts with the Lewis machine gun at targets on the ground and despite his precarious position scored a substantial number of hits.

Although the above test was made a full 10 months before the start of World War I, the only British aircraft equipped with machine guns at the outbreak of hostilities were two seaplanes of the Royal Navy Air Service, and even then they were not permanently mounted. All planes sent to France by the Royal Flying Corps were unarmed when the first British pilots crossed the channel on 13 August 1914. Aircraft at the time were constructed far too lightly to carry very heavy armament. The planes were regarded as of value only for scouting and observation work, without being suitable for inflicting damage on the enemy. Aerial warfare was as yet unknown, although sometimes a pilot took with him a rifle, revolver or a few hand grenades, with which to answer the derisive and obscene gestures usually tendered at such an encounter.

German observers, besides carrying standard military bolt-action rifles, sometimes found it convenient to be provided with a self-loading arm. The most popular one was the highly advanced gas-operated Mondragon, the invention of a Mexican officer, Manuel Mondragon, patented on 8 August 1904, and adopted by his country's army in 1911. It was manufactured in Switzerland by the Schweizerische Industriel Gesellschaft at Neuhausen on the German border. At the beginning of World War I, all production was diverted to Germany. Large numbers of specially designed magazines holding 30 cartridges each were made up and issued to the observers. They remained in use only until the mounting of flexible full automatic guns.

On 22 August 1914, two young British pilots, Lts. L. A. Strange and Penn Gaskell, helped to make aviation history. These two officers, acting on their own initiative, placed a Lewis gun aboard their aircraft and took off looking for the

enemy. In a very short time, at an altitude of 5,000 feet, a German Albatross was seen approaching. Using every known means of coaxing their aircraft along, the aviators could not get closer than an estimated 1,000 yards. Seeing that they were being outdistanced, Gaskell took aim with his Lewis gun and fired an entire drum at the German plane. The pilot and observer of the German aircraft flew on unharmed and perhaps never knew they were the party of the second part in another of aviation's historical events. For this was the first record of a machine gun being fired at an enemy in the air.

After returning to their home field the officers recorded their initial attempt in a full report of the incident. They stated that, although they did not inflict any visible damage to the enemy, there was every reason to believe that machine guns could easily replace the rifles, bricks, pistols, etc., then carried by practically all pilots on both sides.

Strange and Gaskell were in for a rude awakening if they thought progress would come from their dramatic effort. The report resulted in an order by the High Command prohibiting the use of machine guns in aircraft. Such a practice would only cause the pilot to seek out other enemy planes to try out this newfangled idea, thereby diverting his attention from watching troop movements and spotting artillery fire. The latter, it was pointed out, was the primary duty of the pilot and observer and the excuse for the aircraft's existence in warfare. For a brief time this directive stopped such unorthodox practices as far as the British were concerned. Such an attitude is surprising since the British originally became interested in the Lewis gun as a superior aircraft weapon, and England was one of the first European countries to fire a machine gun from the air. It is perhaps logical to assume that the British did not desire to be the first to introduce a type of warfare that could easily have unpredictable consequences.

In any case the order did not stay in effect too long. Before it was rescinded, British aviators had brought down a few German aircraft by plane-to-plane rifle and pistol fire and, in one instance, by a shotgun loaded with buckshot. Only a few days later a machine gun was used by Lts. C. W. Wilson and C. E. C. Rabagliati to shoot down a German plane at Le Quesnoy behind the British lines. By the end of September 1914 a few British aircraft began to arrive at French flying fields each armed with a single Lewis free gun.

The weapons were mounted to fire only backwards, downwards, and upwards; forward firing was prohibited by the whirling propeller of the tractor-type plane. Because of this factor the pusher plane was given high priority in development for fighting purposes, although the tractor in every other respect was much to be preferred. Soon afterwards Lewis guns were mounted on brackets outside of the propeller arc of tractor planes. The weapon was fired by a mechanical triggering device operated by either the pilot or the observer.

From the start the Lewis gun was considered a superior weapon for use in the air. Dirt and foreign material were precluded from getting in the operating parts, and its extreme lightness made it an ideal free gun. Issuance to the air force of a 96-shot drum in place of the 47-shot one furnished a much needed ammunition reserve and gave British pilots the assurance of the best possible aircraft weapon.

Shortly after the larger drum made its appearance during the Somme offensive of 1916, the

A Cartridge Catcher, Designed to Keep Spent Cartridges from Striking the Airman or his Ship when Firing at the Enemy.

Forward-Firing Lewis Machine Gun Mounted on a Pivoting Bracket so the Magazines Can Be Changed.

stock was removed and spade grips were substituted. This made a better balanced gun and the change was met with enthusiasm by the English flyers. The drum-fed gun, when used on a free mount, could be maneuvered suddenly at any chosen angle without fear that the belt of cartridges would swing loose, as in the case of a belt-fed device.

Lewis, encouraged by the success of his weapon, informed the United States Navy, through Commander J. P. Jackson, on 23 May 1916, that he intended to design an automatic machine gun somewhat similar to the one in current use. The finished product, however, would weigh only half as much and have the general appearance and silhouette of the United States infantry rifle. It would be clip fed and fire full automatic. He pointed out that such an automatic rifle would be invaluable not only for aircraft armament, but also for quick assaults as executed by Marine landing parties, since it gave a small body of men the fire power of many their number. Lewis further stated that, when completed by the use of a device to reduce the kick or recoil, it could be fired full automatic from the shoulder of a comparatively strong man. It seemed also to be his plan to permit the new gun to be fired single shot, as he described it as being as accurate when fired singly as our conventional army rifle. It is not known whether Lewis ever undertook such a weapon. Certainly all evidence seems to indicate he did not.

The great powers fighting Germany used the Lewis gun with such satisfactory results that their leaders, both civilian and military, seemed pressed for words to praise adequately its reliability under battle conditions. Even the Germans complimented its deadly performance by nicknaming it the "Belgian Rattlesnake," because of Belgian tactics in waiting concealed with the Lewis and firing without warning other than the sudden hail of bullets.

The Controversy over the Lewis Gun in America

It is a matter of record that Great Britain, Belgium, and France bestowed many honors on Lewis, together with financial backing in producing his weapon. At the same time a dispute arose between Lewis and this country's Ordnance Department on the merits of the gun. Regardless of who was at fault, no one but the future enemy benefited from it and an appalling state of unpreparedness for machine-gun warfare resulted. While the colonel complained bitterly that his weapon was being considered with a "strictly negative attitude," written reports of the office of the Army's Chief of Ordnance indicate that it was just as upset over inability to get the Automatic Arms Co. to submit one or more weapons for testing. It wished to give the guns fair field and endurance trials in accordance with Army regulations.

A memorandum from the Chief of Ordnance at the time is given verbatim in order to show that a conflict of opinion existed. It should be remembered that well before the report was written, 40,000 Lewis guns had already been battle-tested both on the ground and in the air and acclaimed by their users the "greatest single contribution to the Allied cause." The report of General Crozier, Army Chief of Ordnance, dated 17 June 1916, is as follows:

"1. The Lewis Machine Gun was first offered to the Board of Ordnance and Fortification by a letter dated 2 May 1912, from the Automatic Arms Company, inviting attention to an air-cooled, gas-operated, automatic machine gun, and asking for a field test. Mr. R. M. Calfee, attorney, and Mr. Huberty, machinist of the company, appeared before the Board and exhibited the model of the gun. Arrangements were made for the Board to witness a firing test of the gun at Fort Myer, on May 3. . . .

"2. The Board, on June 6, 1912, resumed consideration of the letter dated May 2, 1912, from the Automatic Arms Company, presenting an automatic machine gun and asking for a field test. Members of the Board witnessed a firing exhibition of the gun at Fort Myer, on May 6.

"3. The Board recommended that the Automatic Arms Company be informed that 'the kind of test proposed by them has limitations which the Board does not care to accept, for the reason that the field test proposed usually follows tests made to determine the mechanical suitability of a weapon; but if they will submit a gun for such tests as seem suitable to determine its fitness for the service, it will be subjected to the tests usual for guns of this class under the Ordnance Department, including a field test. Their representatives will be permitted to be present during the tests, and the company will be furnished with a copy of the report.'

"4. The Board of Ordnance and Fortification, at a meeting on July 2, 1912, considered a letter dated July 1, 1912, from the Automatic Arms Company, requesting reconsideration of the action in regard to a field test of their gun. The Board recommended that 'the Automatic Arms Company be informed that after careful consideration of their letter the Board is of the opinion that the usual procedure should be followed, namely, the gun must be submitted to a technical test by the Ordnance Department. During this test, the representatives of the company will be permitted to be present and, preliminary to the test, to give such an exhibition of the performance of the gun as they may see fit, in the presence of the representatives of the Ordnance Department charged with the technical examination of the gun. After this demonstration is completed the gun will then be submitted to such tests as the Ordnance Department may-deem necessary. Ammunition for such exhibition and tests will be furnished by the Government.

"'The parties representing the gun may have the privilege of declining to subject it to any portions of the test which may be proposed to which they may not wish to have it subjected at the time, but in respecting their wishes in this regard the report of the test will, of course, state the facts.

"'In the course of the complete test, the gun will have the kind of field test which they desire, and copies of all reports in regard to the test will be furnished the company.

"'It is also recommended that the company be informed that the Board has no objection to the gun being fired at Monterey, before the

British Troops with Lewis Guns Resting Between Attacks.

School of Musketry, or at College Park, by the Signal Corps, but such tests will have no weight whatever until the technical tests have demonstrated the structural efficiency of the gun.'

"5. The Board of Ordnance and Fortification, at a meeting on March 6, 1913, considered a 'letter dated March 5, 1913, from the Automatic Arms Company, presenting for consideration with a view to its adoption as a type for use in service, their .30-caliber, air-cooled gun, and requesting that the gun be given a thorough competitive test by a board of officers from the several arms of the service engaged in the manufacture and tactical use of machine guns. . . .

"'It is recommended that the Board of Officers be appointed as requested by the Automatic Arms Company, the Board to carry out a competitive test of all models of machine guns submitted. . . . The Board should also make such tests as will determine the value of the guns for use for war purposes from airships, and the suitability of guns and mounts for use for attacking airships from the ground. . . .'

"6. In the above record, no mention is made of the fact that the gun submitted by the Automatic Arms Company is the Lewis Machine Gun.' However, in view of the fact that Mr. Calfee represented the Lewis gun at the test, there can be no question but that the gun referred to in the correspondence with the Automatic Arms Company is the Lewis Machine Gun.

"7. The Board convened for the competitive test of automatic machine guns submitted to it, met at the Springfield Armory on September 15, 1913. The Lewis gun submitted to this Board and tested by it, was one of two model guns manufactured in England (serial numbers 39,153 and 39,930). It is presumed that the guns were manufactured by the Birmingham Small Arms Company, of Birmingham, England, in view of the fact that on July 18, 1913, Mr. Calfee, as Secretary of the Automatic Arms Company, acknowledged receipt of rifle tools and gages shipped to Colonel I. N. Lewis in care of the Birmingham Small Arms Company.

"8. In the 1913 test, seven different makes of automatic machine guns were considered and tried out. The Board consisted of two officers of the Infantry, one of the Cavalry, one of the Field Artillery, and an Ordnance officer. The arsenal test narrowed the competition down to the present service machine gun--the automatic machine

rifle, caliber .30, model of 1909, and the Vickers Rifle Caliber Gun, Light Model. It was not desired to adopt a gun on simply an arsenal test, and three additional Vickers guns and four automatic rifles, caliber .30, model of 1909, were submitted to the Board for an extensive field test, which was held at Texas City and Leon Springs, Texas. As a result of this test, the Board recommended the adoption of the Vickers Rifle Caliber Gun, Light Model, and the Vickers Tripod, Model J.

"9. The new gun differs in one essential from the present gun in that it is water-cooled instead of air-cooled. It is slightly heavier when filled with water than the present gun, the weights being about 29 pounds and 36 pounds, respectively. The cost of the new gun is about twice that of the present gun, unless a tripod be added to the latter, in which case it would be about one and one-half times as great.

"10. This test, in so far as the Lewis gun is concerned, indicated that the mechanism had not been developed to a satisfactory stage, having, in the endurance test, 206 jams and malfunctions, 35 broken parts, 15 parts not broken but requiring replacement, as against respectively 23, 0 and 0 for the Vickers gun, and 59, 7 and 0 for the [Benét-Mercié] automatic machine rifle, caliber .30, model of 1909.

"11. The Board concluded, after a careful consideration of the data collected, together with the knowledge of the suitability of the various designs of machine guns gained by observation during the tests, that 'the Lewis Automatic Machine Rifle, as at present designed, is not considered superior to the service automatic machine rifle, on account of failure to maintain continuous fire, the large number of parts that were broken, and the large number of jams, many of the latter being reduced only after much difficulty and considerable time.'

"12. The Lewis gun was therefore not given the field test, in view of the fact that the Board recommended a competitive test of this nature for the Vickers gun and the Automatic Machine-Rifle only.

"13. On the conclusion of the field tests at Texas City and Leon Springs, the Board expressed the opinion that when the present service machine rifle (automatic rifle, model of 1909) was originally tested some seven years ago, it was then without doubt the best type of machine gun in existence, but during the past seven years the Vickers Company have developed a gun which not only overcomes all the serious defects inherent to the service type of Maxim gun (model of 1904), but compares very favor-ably in weight with the automatic machine rifle, caliber .30, model of 1909.

" The service machine rifles furnished the Board for test were well made and finished, and only a small number of parts were either broken or replaced during the test, indicating that the large number of jams and stoppages of fire which occurred, particularly during the field firing, were not due to either defective material or workmanship.'

"14. Effort has been made from time to time,

A Device for the Lewis Gun Allowing It to be Fired from the Shoulder with Ease.

within the past year and a half, to obtain a Lewis Machine Gun for further test. These efforts have not been successful until recently, when satisfactory arrangements were made with the Savage Arms Company, of Utica, New York, the American manufacturers of the Lewis Machine Gun, to submit a gun to tests similar to those held in the competitive trial of machine guns, in 1913. The Board testing this gun was composed of one officer of Cavalry, one officer of Infantry, and one officer of the Ordnance Department. . . .

"15. In order to further test this weapon, arrangements have been made for the purchase of three Lewis Machine Guns, chambered for British ammunition, which it is intended to mount on aeroplanes on the Texas border and in Mexico. These weapons have been procured with a view to determining whether this particular type of gun has peculiar and special adaptability for aeroplane work."

Very few things in American military history have produced as much controversy and as many contradictory opinions from people in high office as did the failure to procure the Lewis gun for the services. A few quotations are given to show the position held by defenders of the Lewis gun against the Army's claim that it was unserviceable when tested by it.

Sidney Brooks, a British publicist and correspondent, wrote in the Philadelphia Public Ledger on 14 February 1917:

" . . .But there has recently been an even more striking instance of the discrepancy between British experience on the one hand and the views of American officialdom on the other. I refer to the controversy over the Lewis machine gun. Here again I speak simply as a layman and not at all as an expert. But I do know, and every Englishman knows, that the following statements are facts:

"First. That the present war is so largely a war of machine guns--I remember Mr. Lloyd George stating that more than ninety percent of the casualties were due to them alone--that whereas at its beginning we had only two to each thousand men, we now have thirty-two.

Flexible Lewis Machine Gun Mounted on a Scarff Ring.

"Second. That of all the machine guns in use in the Allied armies the Lewis gun is by far the most popular and the most effective.

"Third. That some 4,000 officers and about 400,000 men use it exclusively, and that in the British, French, Italian and Russian armies there are at this moment nearly 40,000 in actual and daily operation.

"Fourth. That virtually all our aeroplanes are armed with Lewis guns, and that of the seven Zeppelins we have accounted for six were brought down by the Lewis gun.

"Fifth. That both on Salisbury Plain and at the machine-gun school in France most of the instruction is done with the Lewis gun.

"Sixth. That it owes its pre-eminence partly to its mobility, partly to its light weight, partly to its capability of being used in any position and partly to the simplicity of its working; and that after fully two years of daily experience in the battlefield it stands higher than ever in the judgment of the British armies.

"Yet this is the gun the American Government virtually turned down. I have heard all sorts of explanation of its action, mainly of a personal or political character. But I have never yet heard it asserted that the Lewis machine gun was rejected by the authorities at Washington on its merits or that they have any better gun or any that is as good up their sleeve.

"Incidents such as these have a somewhat more than depressing effect on an Englishman, who has seen at first hand the terrible effects of a state of unpreparedness and who has no dearer wish than that the United States may be wise in time."

Maj. Gen. Leonard Wood, commander of the Department of the East, declared, "In my private opinion, the Lewis Machine Gun is the best light-type gun yet developed for troops in the field." He added that he favored "having . . . a reserve supply of 25,000 machine guns as in the end one in ten men will carry a 26-lb. machine gun as he now carries a rifle."

Will Irwin, war correspondent for the Saturday Evening Post, declared:

"Modern warfare had developed a real necessity for machine guns both light and heavy, but as far as I saw, the Lewis Gun far outnumbered all other machine guns of the light type among the Allied armies.

"In the last engagement I saw in the recent Somme offensive, whole detachments were going into the trenches with every man carrying a Lewis gun as one would carry an ordinary rifle."

Charles Edward Russell, an American sociologist, wrote in the Cleveland Press, in October 1916:

"Nothing the whole war had brought out has been of so much real use to the British Army as the Lewis machine gun. It has done wonders. It has almost counteracted the British aversion to tactics. . . .

"The merits of the Lewis gun are long past any discussion in British army circles after so many months of testing. It has also added a much-needed redeeming quality to the fame of American products in general.

"One odd little fact is that they nearly all believe the American army to be equipped with the Lewis guns. 'But then you have your Lewises.' British army officers would say to me when the United States was trying to get an army to the Mexican border. 'Rum country, rum country,' they would say when I told them we hadn't."

And from the Army and Navy Register of 30 December 1916 is quoted:

"It appears to be conceded that between sixty millions and seventy millions have been spent for these guns by the Entente Powers, and they are used in all the French and English armies for the first line trenches. Heavier, more durable and water-jacketed machine guns being preferred for the second line. Are all the war authorities of France, England and Russia at fault? If not, why is not the Lewis gun good for the United States?"

There must have been a logical reason for the failure of the Lewis gun to meet the Army's requirements. The most probable explanation was brought to light years later. If valid, it serves as an outstanding example of how certain minute dimensions, which are only slightly out of adjustment, can ruin the performance of a weapon.

When Lewis presented his gun to the Board of Ordnance and Fortification in 1913, it must

Lewis Aircraft Machine Gun, Model 1914, Cal. .303, Twin-Mounted, French.

be remembered that it represented a handmade product in its earliest prototype stage. Constant experimentation was daily being carried on in an attempt to perfect the mechanism. Construction of the gas-operated gun required the attachment of the barrel and receiver so that the orifices in the barrel are at an exact place underneath it. The weapon could then be mass produced and the components quickly assembled. This precluded the conventional means of adjusting head space by screwing in or out on the barrel, as head space was permanently fixed with respect to the barrel and receiver. The only remaining adaptable factors were the angle of the locking cam on the bolt and the straight portion cut in this piece that allowed the piston to recoil a certain amount before unlocking action commenced.

This very critical dimension in first firing attempts has always been determined by trial and error. About the only help engineering can give is to furnish calculations for a safe starting point. The first Lewis guns submitted to the Board were still in highly experimental stage and the gas piston had been designed for the highest rate of fire possible. After the bullet passed the orifice and gas pressure was brought to bear on the piston, the latter had a free movement of 0.875 inches. The spiral cam of the bolt was then engaged by the lug on the gas piston, causing it to rotate and unlock.

The distance of the free movement was such as to give the first weapons an unusually high rate of fire, since unlocking took place while a residual pressure too high for practical use remained in the barrel. The free travel of only 0.875 inches hastened unlocking and caused the bolt to withdraw its support from the base of the cartridge. This slight easing back of the bolt had the same effect as too much head space, and many resulting malfunctions thus occurred. Too, the completed unlocking was done under such pressures that when the empty cartridge cases did not stick or rupture, the bolt was carried rearward with such force from the added blow-back as to overstrain the other recoiling components. This resulted in a parts breakage that was all out of proportion.

Impatient at the delay of the Army Board, Lewis sailed for Europe taking his four guns with him. During his demonstrations abroad, British and Belgian ordnance officers pointed out that his rate of fire was far above what was considered ideal for battle use. In order to reduce the rate, the straight portion of the cam slot was redesigned until it had a free travel or "dwell" of 1.0625 inches. The additional free movement permitted the chamber pressure to drop before the bolt started to relax behind the base of the cartridge. It also established an average rate of fire of around 600 shots per minute when used in conjunction with a fixed gas orifice of .130, a dimension that produced a satisfactory rate of fire and the smoothest performance.

As England was at war and the most trivial

thing concerning machine-gun construction was considered top secret, it is easy to understand why information on this redesigned part was not made available. In fact it is possible that the change may have been made by engineers of the Birmingham Small Arms Co. when the manufacturing drawings were converted from our measurements to the metric system and that Colonel Lewis did not even know of it. When the Savage Arms Co. contracted to make the weapons here in the United States, this change from the original drawings was noted for the first four guns.

It was felt at first that the weapon would not handle the United States infantry rifle cartridge because of its higher velocity, chamber pressure, etc. However, the theory was exploded when the Savage Arms Co. produced its version of the gun. It was basically the same as the unsuccessful earlier models with the exception of the added dwell before the bolt unlocked. The Lewis guns made by the Savage Co. stood the test.

Later Development and Production of the Lewis Gun

General use of the Lewis gun in the air led to the construction of many accessories that made it even more efficient. It was determined by actual battle use that the wind blew the cartridge case deflector and canvas bag back and that sharp maneuvers of the plane closed up the bag, causing stoppages in the ejection chute. As a result, a satisfactory sheet metal deflector and receptacle was designed, which was later replaced by an even better device made of die-cast aluminum.

For aircraft mounting it was found convenient to cut into the gear case above the pin to allow sufficient clearance from the receiver locking pin. Removal of the casing without unscrewing the receiver from its locking piece was thus facilitated. To permit the fitting of an adequate sight, the gas chamber was modified so that the front sight base could be mounted on top with a dovetail fit and retaining screw.

The most urgent demand from Lewis gunner pilots was for a simple indicator to show the number of rounds, if any, left in the drum at the end of a burst or engagement. Many devices were tried, the most successful one being designed and made by the Veeder Manufacturing Co., Hartford, Conn. The counter was mounted on top of the magazine plate and operated by a small gear, the teeth of which engaged in the notches of a latch lock located in the spacer ring. The indicator was set at zero when the drum was filled; after firing commenced, the revolution of the magazine's rim operated the indicator through its gearing. When only 19 rounds we're left in the drum, a luminous figure "one" appeared and stayed until only 9 rounds remained. The number then disappeared and a red marker came into view to indicate to the gunner that the drum should be changed at the first opportunity.

This reliable counter was very ruggedly constructed and was considered the most useful accessory on the Lewis gun. Its acceptance by airmen was of such an enthusiastic nature that one of the indicators was sent in each carton containing six spare drums. The early style drums that were not designed to work with the indicator were soon properly altered.

On 28 May 1918, the Office of the Chief of Ordnance, United States Army, received the following cable from General Pershing: "Request information as to what experimental work has been done towards speeding up Lewis gun in the United States. French are at present doing considerable experimenting along this line; methods pursued being first to increase duration of gas pressure acting on piston by fitting muzzle attachment, which is approximately equivalent to increasing length of barrel by increasing spring tension, adding more length to barrel, and by adding buffer spring in rear end of racks to soften blow against butt tang. Suggest this matter be taken up with Savage Arms Company and reports forwarded to this office."

The Office of the Chief of Ordnance made an inquiry to ascertain the new French rate of fire and how much was desired by the American Expeditionary Force, and received the following reply:

"The rate of fire of Lewis guns should be as high as possible consistent with reliable performance of the gun. The French at present have produced a reliable speed of about 850

Lewis Aircraft Machine Gun, Model 1918, Cal. .30, with 97-Round Magazine and Muzzle Booster.

shots per minute. A speed of over a thousand per minute has been attained but performance of gun has not been satisfactory."

No attempts had been made in this country to speed up the gun, as it had just been adjusted to work satisfactorily at its normal speed. But upon General Pershing's suggestion an order was placed with the Savage Arms Co. for experimental work of this nature, ft was recommended that a rate of fire of 900 rounds a minute would be acceptable. The company made up a special spade grip, with two buffers having heavy springs to act against the end of the feed operating stud and rack. A hardened buffer plug was added at the end of this part. And to increase the force of recoil of the gas piston greatly the orifice was opened up from .130 to .190. The latter change was found upon test to be far too great for smooth performance. It resulted only in having the extractor tear through the rim of the empty case which was still under terrific gas pressure. The company officials were unable to lire a single full drum of ammunition without some serious malfunction or parts breakage.

Without expending further effort, the Savage Arms Co. asked permission to give up the experiments as an impossibility. The Ordnance Department was not so easily discouraged. It ordered Savage to reduce the gas orifice from .190 to .150 and put the Hazelton attachment on the muzzle. The device trapped the gas momentarily after the bullet had cleared the muzzle. A high residual pressure was held in the bore to add greater operating power and recoil to the piston stroke. This modified assembly increased rate of fire greatly but it resulted in wearing off the stop, rebound and feed pawls, after the firing of a few magazines. Innumerable failures to feed resulted.

The fault was finally overcome by continued firing and experimental heat treatment of the affected parts until the breakage stopped. Thereafter one Lewis gun was fired as much as 8,000 rounds, when the rate of fire was 800 to 850, without what was considered excessive wear. As many as 1,000 shots a minute were obtained by restricting the orifice in the muzzle attachment, but a high percentage of broken parts again resulted when the orifice was thus choked. It was decided that a maximum of 800 to 850 rounds per minute could be fired without affecting the reliability of the gun's action. The most serious difficulty encountered at the latter rate of fire was the tendency of the powder gas to blow back into the operating parts and clog or foul up the recoiling mechanism. It was remedied by drilling three holes, 0.0625 inch in diameter, through the cylinder and casing a little ahead of the rearmost position of the piston head on recoil.

All modifications were officially approved and 5,000 muzzle boosters were ordered from the Savage Arms Co. to be attached overseas to Lewis guns already in action. Before this was done, it was found more desirable to complete the

speeded-up gun at the factory, since it had been apparent that the ramps on the receiver needed a milled-out cut. This could be done in a satisfactory manner only in a well-equipped manufacturing plant. After the modification was done, only a limited number of the improved guns were actually delivered.

The Savage Arms Co., having been a large and efficient armament factory for half a century before the war, was considered well equipped to furnish all the standard-type Lewis guns needed for United States military service and no contracts were made with other plants. The original order for the ground gun was placed during the latter months of 1917. By May 1918 more than 16,000 had been produced and delivered. Over 10,000 of these were of the aircraft type; the other 6,000 were delivered to the Navy for Marine Corps use. By August 1918, 25,000 of the aircraft type alone had been made and by Armistice Day, 34,000 of this model had been delivered.

The Savage Arms Co. must be credited from the very start with keeping production ahead of requirements and overseas supply was held up only because of shipping difficulties. There were comparatively few insoluble manufacturing problems in the production of the weapon. This can be rightfully attributed to the foresight of Colonel Lewis in emphasizing simplicity of manufacture.

Because the bolt was held in a cocked position, the Lewis gun could not be synchronized to fire through the propeller arc as could front-seared machine guns. This limited its method of mounting, although many novel ways of firing outside the propeller arc were tried, a number of which were successful.

The main use of the Lewis was as a free gun. At first it was necessary to modify the ground weapon to mount in a plane, but an aircraft model was soon issued that could be easily adapted to any kind of mounting desired. It was first installed on biplanes over the observer's seat by means of a tourelle. Often two guns were placed together in a yoke and the torque action of the yoke combined with a knuckle arrangement permitted a perpendicular action of the mounting. Aiming in all directions was thus made possible. Both guns could be fired simultaneously by means of a Bowden connection. A recoil reinforcer was sometimes added to the mounts to make the operating action more positive and to increase its rate of fire to a limited extent.

When certain altitudes were reached, freezing up of guns was a common complaint. In this situation various methods were employed to heat the operating parts. An electric heater, obtaining its power from the motor's generator, was usually attached under the feed cover.

The front sight was originally made of bronze but combat conditions proved the metal too soft to be satisfactory, as the set screw could not hold the sight in place. The easily burred material allowed the base to loosen. Steel sights had to be made to replace the original ones.

A simple set of magazine rim and spacer pin gages for use in the field by ordnance men was developed. Their intended purpose was to give a quick means of checking accurately the critical dimensions of these two parts. On the standard gun firing at 600 rounds a minute, it was thought a recoil check or muzzle brake, used over the muzzle, would result in smoother performance by eliminating the kick. However, when a test was made with such a brake designed by the French, so much carbon and fouling was found in the mechanism that the idea was dropped.

Use of the Lewis Gun by the Navy

One of the most peculiar things about the Lewis controversy is that the Navy did not concur in the belief that the weapon was unreliable. The Navy, in its effort to supply the Marine Corps with an adequate light machine gun, had the Marines test the weapon. Complete satisfaction with its performance was expressed.

In September 1917, an officer from the Aviation Ordnance Section, Lieutenant Commander Stone, who had been sent abroad to collect data and specimens of foreign aircraft ordnance, returned to the Bureau with voluminous information and a quantity of English and French aircraft armament, among which was a British Lewis gun.

The Navy ordered the Savage Arms Co. to modify the standard Lewis gun to conform to the sample submitted so that it would be

identical with those used by Great Britain and France For both aviation and ground use. These instructions were complied with and large quantities were delivered to the Navy by 1 January 1918. From that date the Navy never suffered for lack of machine guns. Since there was an ample supply for training the Marines at home and outlining them before going overseas, they were the only American troops to arrive in France armed with Lewis guns. Other units were given whatever the French and English high command could conveniently spare, the Chauchat being offered in most cases.

U.S. Marine Training with a Lewis Gun, 1917.

The Navy was long an interested party in machine-gun development. It had adopted the Colt '95 model while other branches of the service still clung doggedly to the hand-cranked Catling. It was realized early that the Lewis gun would best suit Naval needs in World War I for both land and air use. Having previously been satisfied with its performance, the Navy ordered enough weapons, in advance of the war, to give it an adequate supply for training purposes. Once this need was met, an ever-increasing flow from the factory kept ahead of the demand.

Such foresight was due to a large extent to the efforts of the newly formed Naval Aviation Ordnance Section, created after 6 April 1917, as a subsidiary of the Gun Mount and Small Arm Section. On 1 October 1917, the unit became officially known as the Aviation Ordnance Section. The section had under its cognizance responsibility for obtaining machine guns, sights, mounts, ammunition, bombs, and pyrotechnics, along with any other large caliber guns as long as they were intended for use in aircraft. After war was declared, Lieutenant Commander Stone, an officer from this section, was sent to the front, as mentioned above, to gather samples of the best weapons with which to fight an aerial war.

While the new section's complement was very small and its quarters cramped, it certainly proved competent in every respect. The reason for its existence was best stated in its letter of organization:

"To plan and develop by years of experience, the needs of Naval aviation and base its requirements under conditions of war, and never upon those of peace. The principal function of this organization is to harness authority and responsibility so that they can never be separated. . . . so that a designer cannot design a gun, then throw credit or blame onto the producer, or later escape the final issue and responsibility therefor. One man is to be responsible for each bit of material or development from its start to completion . . . . its issue, its service performance, and later its overhaul or repair. Given this responsibility, he is to be clothed with the requisite authority over all its details."

One of the unit's first acts was to place contracts for the Lewis gun. It had expressed dissatisfaction with the heavy water- and air-cooled

automatic weapons that had been previously tested. The Savage Arms Co., already tooled up for the caliber .303 Lewis gun for the British, had been approached as early as 5 February 1917 (before the section was set up) on the production of sufficient caliber .30/06 guns for Marine Corps testing. Through the hard labor of an already overworked factory at the urgent insistence of the Navy, this was done and by 5 April 1917, one day before declaration of war, successful acceptance tests were run by both Navy and Marines. On 25 April 1917, the first contract with the Savage Arms Co. was given for 3,500 guns. A second followed on 22 June 1917, for 350 more; a third on 6 April 1918, for 2,500; and a final one on 13 June 1918, involving 3,000 additional guns.

A total of 9,350 guns with spare barrels and accessories was delivered in time for actual service before Armistice Day. All reports concerning use of the Lewis gun under combat conditions stated it was indeed most reliable, and could be fired and serviced by a single gunner. Although jams and stoppages were infrequent, little difficulty was experienced in clearing them when they did occur.

One of the most inexplicable acts of World War I, and one that curtailed American combat use of the Lewis guns, happened when the Marine divisions arrived in France, fully equipped with the weapon. They were soon attached to Army units and under the command of the latter, they were ordered to turn their Lewis models in. Greatly inferior Chauchats were issued as replacements.

The Routing of the Zeppelin Menace

If the Lewis gun had not fired another shot during World War I, its part in breaking up the Zeppelin raids over England would have more than compensated the Allies for the cost and effort expended on its production. The German aircraft was named for its inventor, Count Ferdinand von Zeppelin. He was born on 8 July 1838 in Constance, Baden, Germany, and after over 30 years of service in the German Army retired in 1890 with the rank of general. He announced his intention of devoting the remainder of his life to the study of aeronautics and the building of lighter-than-air machines. His decision was influenced partially by his term as military attaché in the United States during the Civil War, at which time he made his first balloon ascension with Professor Lowe to reconnoiter the Confederate forces.

Unable to find financial backing at first, Count von Zeppelin sold his family estate and all other valuables in order to raise the $150,000 needed to conduct his first experiment. Within 2 years the inventor had his first airship, using a 16-horsepower Daimler motor for power, ready for flight. After a short trial in the air, it was destroyed by an accident, as were also Zeppelins II, III, and IV. The indomitable count was financially ruined after so many failures and very low in morale, when the German Government agreed to finance the next airship, to be known as the Deutschland. Through tireless effort on the part of the inventor and his assistants, a craft was produced capable of carrying passengers with comparative safety. In 1910 it made such a flight for a distance of 300 miles. This feat stirred the imagination of the German people and over $1,500,000 poured in for the purpose of more experimentation.

The Deutschland was also wrecked by a sudden and violent wind as it attempted to land, but the government now had implicit faith in the Zeppelins. Further experiments showed that greater engine power was needed, and one of the dirigibles powered with 75-horsepower engines successfully rode out a storm for 3 days with gales at times of 80 miles per hour. Between 1900 and 1914 the Zeppelin Corp. constructed over 115 airships of the rigid type.

Up to this point Germany had practically a monopoly on dirigibles as other European countries had dropped them in favor of heavier-than-air models. The German military command realized that it had at its disposal what might constitute a powerful weapon, as the Zeppelins could stay aloft hours longer than conventional airplanes. They could also reach a greater altitude than any plane. Their speed, especially with a favorable wind, was far in excess of that of standard military aircraft. Best of all, the designers reasoned that the huge area and unlimited carrying power of the dirigibles furnished a platform upon which to mount weapons. This would

Lewis Machine Gun, Model 1917, Cal. .30.

allow them to fight off anything that dared approach the flying arsenal.

As one very enthusiastic supporter explained, "For an airplane to engage a Zeppelin with the limited armament the plane could carry would be like a canoe attacking a battleship." Since the Zeppelin could reach prohibitive altitudes and needed no weight limitation on the number of machine guns and even cannon that could be mounted, the arguments of its supporters seemed to be too one-sided even to be logically disputed.

Although Germany had built up a mighty Zeppelin fleet, she most certainly had not done so at the expense of her heavier-than-air machines. Her military leaders knew, however, that every other major power in Europe had an air force of conventional-type planes equal and, in some instances superior to, her own. They earnestly believed that the Zeppelin was Germany's ace weapon and that, when "the day" arrived, the mighty ships would cruise unmolested to and from strategic targets deep in enemy territory.

This belief was not a German monopoly, as the French and British begrudgingly accepted it in every respect. Such a generally conceded point of superiority gave the Germans a psychological weapon in itself. From the outbreak of hostilities, they released propaganda building up horror in the Allied countries that Zeppelin raids and the destruction of unprotected cities were certain to follow.

As a result of constant predictions of impending doom by journalists and military experts, the general public was left in a state of near hysteria at the mere thought of the inevitable Zeppelin raids to come.

It was fortunate that the Germans also believed in the invincibility of their "Air Armada." Feeling so secure, they disregarded observations supplied by their secret operatives that British pilots had been firing in their Lewis guns newly designed ammunition recently patented by George Thomas Buckham of London.

The first Zeppelin assault on England took place at Great Yarmouth on 19 January 1915. It resulted in minor damage and was considered merely a token raid, a dress rehearsal for the main event. An English newspaper made the statement: "What made the people indignant was not so much the ruthlessness of the Germans, but the failure of their own naval and military to offer any protection . . . or even to harass them when they came."

It took years in time and millions in money to build up the Zeppelin myth, but it was shattered quickly when British airmen found the fatal weakness of the huge airships. The following report on bringing down a Zeppelin, the L-53, by Lieutenant Culley, of the Royal Air Force, illustrates a typical encounter:

"The naval units informed me at 8:30 a. m. there was a Zeppelin approaching from NE at an estimated 15,000 feet altitude. I got my 'Camel' into the air at 8:41 a. m., and with the sun at my back, I climbed upwards. When first sighted, the airship was broadside but evidently having sighted me it had turned end on and had climbed to 19,000 feet. As we approached, the Camel sat tail down unable to climb another

inch of altitude. At this close point the airship started to pass slowly overhead. I pressed the trigger of my two Lewis guns mounted above the wing and after firing a long burst observed the bullets strike and flash as they hit the metal in the under belly structure of the huge ship.

"A propeller on an engine on the port side was seen to stop and as nothing else seemed to happen I dived my plane, followed a moment later by an explosion as the whole airship exploded in flames. One of the crew succeeded in jumping with a parachute and was saved."

Lieutenant Culley could have mentioned the fact that he was using the new Buckham incendiary bullets in his guns.

Destruction of the Zeppelins with the deadly combination of the Lewis gun and incendiary bullets gave English and French morale its greatest boost of the war. The weapon with its highly inflammable ammunition literally shot the dirigibles out of the air. Of the 12 Zeppelins destroyed in attacks over London, the Lewis is officially credited with shooting down 10 of them.

The Buckham incendiary bullet consisted of a Hat-nosed cupro-nickel jacket, containing in its nose an 8-grain charge of yellow phosphorus. The charge was held in place by a serrated plug of lead backed up by a larger base plug of the same material. A small hole through the jacket, located near the junction of the two plugs, was filled with a low fusible alloy. The latter melted as the bullet passed through the bore and permitted the phosphorus to ignite.

The yellow phosphorus, when brought into contact with the highly flammable hydrogen gas-filled envelopes of the great airships, resulted in immediate fire and explosions. The metal framework inside the dirigibles increased the hazard as the flat-nosed bullets, upon striking a support member, had a tendency to rupture and scatter the flaming mixture over a wide area.

Thus in a comparatively few months the death knell was sounded for the great German menace, the Zeppelin. The people of Great Britain and France, being relieved of the horror of mass annihilation by the successful employment of the Lewis gun, looked upon it with more admiration than is usually accorded a common weapon of war. They felt their governments could not give too much official praise and credit to it.

Colonel I. N. Lewis, U.S.A. (Retired).

Conclusion

It would be possible to write an entire book on why the United States seemed to ignore the Lewis weapon when machine guns were so desperately needed. Regardless of who was right or wrong, or for what particular motive, other than intense patriotism, the fact remains that Colonel Lewis sent to the Secretary of War certified checks for over a million dollars, representing his portion of the royalties on Lewis guns bought by the United States, during and following hostilities. Lewis's notation was "I will not accept one cent of royalty for a single Lewis gun purchased by the government of my country."

Even the acceptance of the colonel's first check covering his royalties on guns sold to the War Department involved him in a characteristic dispute with General Crozier, the Army's Chief of Ordnance. The check, which was for $10,889.17, was sent for deposit to the credit of the United States Government on 16 February 1917. Mr.

W. G. McAdoo, the Secretary of the Treasury, asked the War Department for an opinion on the propriety of accepting the donation, especially since the Savage Arms Co., which paid the royalties to Lewis, was still competing for Government orders. General Crozier prepared a memorandum saying that acceptance of the check would not embarrass the Department in dealing with the Savage Co. Then he continued with some adverse comments on Lewis's claims that he had never sought pecuniary recompense from the United States Government for his inventions, and that he had never had any assistance or encouragement from the Ordnance Department.

Colonel Lewis was advised by the Secretary of War, Mr. Baker, of the general's comments and his reply follows:

"No. 1 Russell Terrace, Montclair, N. J.,
May 12, 1917.

'The Honorable the Secretary of War,
          Washington, D. C.

"My Dear Mr. Secretary: Your letter of April 29th, with its inclosed memorandum from the Chief of Ordnance, has been received and very carefully considered.

"I do care to have the money represented by the check sent you in my letter of February 16th, 1917, deposited in the Treasury of the United States simply on the ground stated in my original letter, without any understanding that you are now examining or undertaking to determine any controverted question as to the breach of relations between me and the War Department or any branch or division of it, and I now have the honor to request again that you so accept and deposit it.

"My letter of February 16th, 1917, was sent you solely for the reasons stated therein and for no other.

"I can see no possible embarrassment to the War Department nor to the Ordnance Department in the acceptance of my check. It is possible, however, that your acceptance and deposit of the check may embarrass the present Chief of Ordnance personally.

"The memorandum from the Chief of Ordnance to which you invited my attention is so widely at variance with what I know from personal knowledge to be the facts in the case that I can not fairly consider any of the questions raised by Gen. Crozier therein without controversy, and I understand it to be your wish and direction that there be no further controversy.

"In the present very grave national emergency I am directly instrumental in supplying, delivering, and putting on the actual firing lines against the fighting enemies of my country more machine guns each week than the present Chief of Ordnance has supplied for the use of our

Royalties Returned by Colonel Lewis.

own Army of defense during the whole of the 14 years that he has been in office. I have done, and am doing, this without one penny of assistance and without one word of encouragement or acknowledgment from anyone connected with the Ordnance Department and in spite of the long-continued and active opposition of that department.

"I am therefore content to now rest the matter with you simply as a personal appeal for justice.

"Very respectfully, your obedient servant,

"I. N. Lewis,
Colonel, United States Army (retired)"

General Crozier found no objection to accepting the colonel's check and it was deposited in the United States Treasury in the name of Isaac N. Lewis, on account of "Donation to the Government." No such difficulties accompanied later refunds made by Colonel Lewis.

As might be expected, the Lewis gun did not go out of existence following World War I. It saw much use in the hands of the United States Marines in the Nicaragua campaign, and it was the favorite infantry arm for many smaller countries long after the major powers sought to replace it with a more efficient weapon. The Norwegians made it under license in a 6.5-mm caliber and it is the only light machine gun definitely known to be used by their army. Japan produced it under the designation Models 1929 and 1932.

In fact, the Lewis gun, although it had undergone practically no change for three decades, was still on hand by the thousands in this country at the beginning of World War II, a fact that was most fortunate for the Allied cause. When the Germans practically disarmed the British army in the debacle at Dunkirk, 80,000 Lewis guns were purchased by England from the United States and other friendly powers. And when the Japs struck at our fleet on 7 December 1941, the first pictures rushed back from Hawaii showed the old reliable Lewis being used as a makeshift antiaircraft gun.

After the arms situation in Britain got back to normal, the thousands of Lewis guns were given to the home guard and to small units in the fleet. It is recorded that on more than one occasion the outmoded guns brought down planes that made the fatal mistake of coming within range of the gunners, who in many cases were veterans of the first World War and no strangers to the Lewis gun.

Models of the Lewis Gun

The various models of the Lewis gun and the countries using them were too numerous to list in the text. As a handy reference, they are tabulated herewith:

Country	Designation	Bore
(1) Ground
U.S. Test	Model 1911, (one, handmade)	.30/06
U.S. Test	Model 1912, (4 manufactured)	.30/06
Belgium	Model 1913, Liége (A few were made in Belgium during this year, before contract was transferred to Birmingham Small Arms.)	.303
Belgium	Model 1914, B. S. A. (This was called "the Belgian Rattlesnake" by the Germans.)	.303
Belgium	Mark VII, B. S. A.	.303
Belgium	Mark VIII, B. S. A.	.303
Great Britain	Mark I (Model 1915, B. S. A.)1	.303
Great Britain	Model 1915 (Savage)1	.303
Great Britain	M1916 (Savage)1	.303

¹ Between the world wars all these were modified to Mark I except those sold as surplus.

Country	Designation	Bore
Great Britain	Model 1916 (Mk VII, B. S. A.)1	.303
Portugal	Model 1917	.303
U.S. Army	Model 1916	.303
U.S. Army	Model 1917	.30/06
U.S. Navy	Mark VI (also Mk VI Mod 1)	.30/06
Honduras	Ex U.S. M1917	.30/06
Nicaragua	Ex U.S. M1917	.30/06
Commercial	Model 1919	.303
Holland	Model 1920	6.5 mm
France	Model 1922	8 mm
Russia	Same as British Mk I	7.62 mm
Japan	Model 1932	7.7 mm
(2) Aircraft
Great Britain	Mk VII Model 1916	.303
Great Britain	Mk II	.303
Great Britain	Mk III	.303
France	Model 1916 (Darne)	.303
U.S.A. F.	Model 1917	.30/06
U.S.A. F.	Model 1918	.30/06
U.S.A. F.	Model 1919	30/06
U.S. Navy	Mark X	.30/06
Italy	Same as British Mk II	.30 & .303
Russia	Same as British Mk II	7.62 mm
Japan	Model 1929	7.7 mm
Japan	Model 1932	7.7 mm

¹ Between the world wars all these were modified to Mark I except those sold as surplus.

Chapter 3
Vickers Aircraft Machine Gun

In the early months of 1916 the British Royal Air Force first attempted to adapt the Vickers-Maxim rifle caliber machine gun to aircraft use. Heretofore planes had in most instances served as flying platforms upon which weapons were mounted to be aimed and maneuvered by the operator. The propeller served as an effective barrier against mounting guns permanently to shoot straight forward. If the latter could be accomplished, it would change the craft into a gun-laying device, as had been done previously by Roland Garros, the great French air fighter. The plane's flight attitude would then govern at all times the bullet trajectory of the forward-firing weapons. The R. A. F. was very conscious of this unused firing area and tried in many ways to put it to use.

By actual test in late 1914 it was found that only 2 percent of the shots fired by a machine gun through the arc of an air screw would hit the blade and that it then required quite a number of caliber .303 bullets to weaken the propeller to the point of being unserviceable. This, the authorities thought, justified the mounting of one Vickers machine gun to fire straight ahead for use in an emergency only. As a result, every pilot upon engagement with the enemy naturally considered it an emergency situation and used the weapon upon all occasions. The arrangement turned out to be a faulty makeshift, for in more instances than deemed necessary a gunner pilot had started home after a victorious fight only to have his propeller disintegrate from bullet holes of his own making. Crash landings resulted, with numerous fatalities or capture by the enemy of valuable ace fighters.

Since the Vickers was belt fed and therefore of little use as a free gun, its part in the early stages of aerial warfare of 1914 was indeed limited. Its streamlining though had been undertaken from the start, many things having been done to cut down its weight and make it more efficient for air use. An example was the replacement of the water jacket with a skeletonized tube and cap to allow cooling by air circulation. This device not only supported the barrel adequately but reduced the weapon's weight to 30 pounds. The handle block was replaced by a flat plate and the front and rear of the covers were milled out to permit various triggering installations. One of the most radical changes was the redesign of the left-hand cartridge box and feed to allow the mounting of two guns adjacent to each other. As another refinement a retracting handle was added which allowed adjustment of the return spring's tension from the rear end of the gun.

But the device that made the Vickers machine gun a superb aircraft weapon was the invention of a reliable synchronizing gear. This brilliant achievement came from the efforts of George Constantinesco, a Rumanian engineer living in London, who had specialized in devices for transmitting power by impulse.

Actually the Rumanian was only one of many attempting to solve this problem. There came into being at about the same time the Scarff-Dibovsky synchronizing gear, developed by Warrant Officer Frederick William Scarff, R. A. A. S., who had made aviation history by inventing the Scarff gunners' ring, and Lt. Victor V. Dibovsky, of the Imperial Russian Navy. It was a mechanical gear consisting of cogs and teeth operating off the propeller shaft. Another such contrivance was invented by Maj. A. V. Bettington, commanding officer of the Aeroplane Repair Section No. I, Aircraft Depot. This was known as the "Arsiad" synchronizer, the name arising from the initials of the major's command. It also was an arrangement of gears, cams, and levers attached from the propeller shaft to the machine-gun trigger. Still another was the Vickers trigger

Vickers Aircraft Machine Gun, Model 1915, Equipped for Synchronizing.
Mount is for Purposes of Photographing Only.

actuator, designed by George H. Challenger, an engineer of the Vickers establishment. The number of approaches from various angles shows the great importance placed upon a solution to this vital problem.

All three of these synchronizing gears depended on mechanical means for firing the gun at the requisite instant. The main operating principle was that a cam driven by the engine and working through a series of push rods and levers tripped the trigger at intervals and was so regulated that the revolving propeller was clear of the line of fire. The mechanism was set in action with a trigger controlled by the pilot. Although effective, these devices were crude and mechanically unreliable, since adjustment of the rods had to be extremely accurate and continued firing might jar the original setting.

The Constantinesco synchronizer, however, did not employ such features in its design. It was based on one of the inventor's earlier patents concerning the operation of a hydraulic rock drill. The impulses transmitted through a column of nonfreezing oil under pressure in a pipeline furnished the energy to depress the trigger at intervals regulated by the position of the blades. A cam on the propeller shaft engaged a lug on an oil pump at the instant the trailing edge of the propeller was clear of the bore of the gun and continued to hold the trigger actua-

Vickers Machine Gun, Synchronized with Propeller in a Pursuit Plane, World War I.

tor down until the leading edge approached. The lug then ran off the cam and the spring-loaded trigger depressor let up on the sear interrupting the fire. The device was operated by a simple oil pump that furnished pressure until the leading edge of the propeller started to line up with the gun muzzle. At this point it released tension only to take it up after the blade passed.

Overnight all mechanically operated synchronizer gears were obsolete. Manufacture was started at once by the Vickers Co. and the first model made by this firm was successfully demonstrated on a BE2C in August 1916. It showed perfect reliability and was adaptable to any type of airplane engine. From then on until the end of the war, the units were fitted to all aircraft as fast as both could be produced. Over 6,000 were installed on British planes alone between March and December 1917, and 20,000 more were added between January and October 1918.

The first planes to go into combat with the hydraulic synchronizer were a squadron of DH-4's which arrived on the continent on 6 March 1917. Two days later two groups of Bristol fighters were fitted with the same arrangement. From then on aircraft with this aid to fire power were delivered at regular intervals. Now the planes could fire straight ahead, in addition to maneuvering one or two machine guns on a free mount.

At first the Constantinesco gear was designed to fire only one machine gun, but it was soon adapted to operate two mounted parallel to each other. The Sopwith "Camel" was the first plane so equipped. It had a fire power of 1,600 shots a minute or, as the British figure it, 40 pounds of projectiles in the same period.

The synchronizing device was so successful that it became a must in British aircraft armament. It was placed in all subsequent models as fast as they appeared. As a result of its introduction on the DH-4s and Bristol fighters, the Allies recaptured supremacy of the air from the Germans, and while there were times when it was

gravely in jeopardy, it was never relinquished for the remainder of the war.

The Vickers gun was ideal for synchronizing because it employed a spring-loaded firing pin. This was released only when the weapon was in battery and the bolt securely locked.

The next officially adopted modification was a speeding-up device invented by Lt. Comdr. George Hazelton of the British Navy. It consisted of a specially designed sleeve and conical spring between the followers and barrel discs. The only other change in the gun was the hardening of the front left recoil plate and the substitution of a much heavier roller washer pin. The latter change was necessitated because experimental firing showed that the ordinary pin vibrated loose.

While the Hazelton attachment accelerated firing up to 1,000 rounds a minute, and one Vickers, so modified, went 14,000 rounds on a test before the first critical break of a component part, this rate was thought to be too high for reliable performance. The booster was then altered to slow the weapon to 850 shots per minute, which was the optimum speed decided upon officially.

The first British planes equipped with the fully modified speeded-up Vickers guns were ordered not to fly beyond their own lines as the changes were classified as "Top Secret" and the Royal Air Force wished to battle-test the improvements thoroughly behind its own lines before beginning mass production. It did not want the Germans to salvage one of its test planes through being shot down behind enemy lines. No doubt memories were still vivid of the forcing down of Roland Garros in German territory and the capture of his bullet deflector which resulted in the reliable Fokker synchronization system.

Another increased rate-of-fire attachment under consideration at the time of the Hazelton device was the invention of Lieutenant Dibovsky of the Russian Navy, who had earlier been unsuccessful in getting his synchronizer adopted. While his booster did get the Vickers well over 1,000 rounds per minute, the action of the gun was so violent that it required many other compensating adjustments to keep breakage from being prohibitive. The parts of the Dibovsky attachment were also very complicated to manufacture. Since the speeds of both the Dibovsky and the Hazelton were practically identical, it was logical that the British adopted the latter.

Both devices utilized the blast following the bullet's clearance of the muzzle to add to the recoil forces and furnish surplus energy to accelerate the recoiling mechanism. The trapped gas expanded in the chamber and, acting on the face of the barrel, shoved it rapidly to the rear.

A great deal of difficulty was experienced in using cloth or fabric ammunition belts in air firing the Vickers, because during a "dog fight" the empty end of the belt would blow back in the pilot's face or become entangled with some part of the plane. The problem was remedied by the adoption of the metal link disintegrating belt. As each cartridge was extracted and fed into the gun, the link would separate from the rest of the belt and either drop in a canvas bag or fall harmlessly over the side. This unique but practical method of feeding the Vickers was invented in 1917 by William de Courcey Prideaux of Weymouth, England, a French civilian who at the time was residing in Great Britain. One of the best features of the disintegrating links was that all Vickers could be modified to use them simply by changing two small parts in the feed system.

As each new problem in aerial warfare

Vickers Aircraft Machine Gun, Model 1919, 11 mm Manufactured by Colt's Patent Fire Arms Co.

Vickers Aircraft Machine Gun, Class "F", Cal. .303.

presented itself, it was solved by some eager inventor. Difficulty in sighting was overcome by the appearance of tracer ammunition in which the base of the bullet contained a mixture that ignited when going through the bore and provided a luminous trajectory from the muzzle to the target. The mixture first used consisted of barium oxide, a very high oxidizing agent, combined with powdered magnesium, a substance that burns rapidly with a visible flame. This, like the other refinements, only added to the deadliness of the weapon. The tracer not only allowed the gunner pilot to correct the course of his plane until his bullets made contact, but in many cases, it ignited gas or inflammable surfaces upon hitting the plane and the victim plunged to earth in flames.

Within a few months armament on all fighting planes had increased tremendously without basic changes merely by refinement of an existing machine gun. The effectiveness of air combat increased proportionately. This short period removed for all time the early semicomical aspect of military aviation; in fact it was an unusual month after January 1917 that did not bring either some radical refinement or an accessory that contributed to the deadliness of air warfare. The machine gun was already far ahead of aviation and only needed application of various theories to make it as efficient in the air as it was on the ground.

During 1917 the Allied air command saw need for an aerial machine gun larger in caliber than the conventional rifle bore for use against observation balloons. The French were the first to modify the Vickers to take their 11-mm Desvignes cartridge in order to provide more of the tracer and incendiary elements.

The Russians were using a larger caliber Vickers than the other Allies and this fact made it the easiest of the various Vickers to modify for the large French cartridge. An order was placed with Colt's Patent Fire Arms Co., Hartford, Conn., to alter a thousand Russian guns to shoot the 11-mm cartridge. When this was done, early firing tests showed that the rifling pitch was too pronounced and threw the tracer element out of the bullet soon after leaving the muzzle. The difficulty was caused by the rifling which cut the bullet jacket too deep and made the rear of the

bullet fan out. When the pitch was changed from one turn in ten to a complete revolution in 22 inches, the performance of the bullet was satisfactory.

The design of the weapons, except for the caliber, was identical with that of the smaller bore guns, and they were accepted with such enthusiasm that large orders were placed both in England and America. An additional order was placed with Colt for 1,700 guns after the company had filled the initial order. The weapon fired at a rate of 600 rounds a minute with an effective incendiary tracer range of 1,850 yards.

American ammunition factories were also ordered to make the new French incendiary bullet. This cartridge and the conventional gun made an excellent combination for attacking observation balloons and firing the gas tanks of fighter planes.

The Russian Vickers was chosen to be altered largely because at this time a revolution was raging in Russia and the Colt Co. could not deliver weapons ordered by the Czarist Government. The Allies, knowing they would have to rechamber the barrels anyway in order to use them, felt they were the most logical ones to alter for the larger cartridge.

The inferior French ammunition, inadequate as it was in some respects, showed aviation authorities that a large bore machine gun or automatic cannon was a necessity in air warfare of the future.

The Vickers-Maxim mechanism was so reliably constructed that an attempt was even made to convert it to an observer's gun, in spite of the fact the Royal Air Force believed it already had the world's best gun of this type. The conversion consisted in putting a 97-shot drum feed on the weapon although belted cartridges could be used if need be. The drum was actuated by recoil of the barrel and barrel extension which engaged a lug with a cam on the circular feed and rotated it enough to index a round in line with the rising T slot on the bolt face.

This large drum protruding above the already high receiver did not make a very compact weapon. Most certainly it could not compare with other machine guns which were more in keeping with conditions of limited space and maneuverability. The location of the drum across the line of sight also made necessary an unusually high and unsatisfactory sighting arrangement. The weapon remained in a prototype form for a few years following World War I.

When motors capable of high altitudes were

Vickers Machine Gun, Mark C, Cal. .50.

finally designed, naturally air fights took place at the new heights and pilots began to have new kinds of malfunctions that were traced to the extreme cold at these altitudes. Reports of stoppages became so prevalent that electric heaters were improvised by ordnance mechanics in collaboration with field electricians. Finally when a heater was made that proved adequate, manufacturing drawings were sent to the Vickers Co. and it was mass produced.

The greatest percentage of stoppages at high-altitude firing came from the gumming up of oil on the mechanism and the resulting sluggish movement caused excessive jams. To correct the situation, the parts were heated by copper pads on each side of the weapon, held in place by the same bolts that secured the cam. As all the moving parts were at one time or another brought into contact with the cam, it was felt that, if the latter was kept hot, it would in turn keep them warm enough to function smoothly under any cold encountered. The weapons were also aided by the type of mountings used. In most cases they were placed in recesses in the cowling with only the top half of the jacket and the bore of the barrel uncovered.

To operate the Vickers high-speed aircraft machine gun, the pilot gunner first places the brass tag end of the cartridge belt, if a fabric belt is used, through the feed block from the right side. With the left hand he pulls it through as far as it will go. At the same time the crank handle is rocked back on its roller to its full limit, and while in its rearward position the belt is again pulled one more space, indexing the incoming round.

The crank handle is now released and flies forward under its spring tension. The sliding face on the bolt moves up when all parts are in battery, allowing its T slot to slip over the cartridge rim. Again the handle is pulled rearward and at the same time the ammunition belt is pulled over the space of one round. When the

Vickers Machine Gun, Mark V, Cal. .50.

belt moves left as far as it will go, the handle is released.

This second cycle places the first cartridge in the chamber and the T slot is over the incoming round in the feed belt. The weapon is now charged for firing. The pilot, when ready, depresses the trigger fastened on his stick and by either a mechanical or oil pump arrangement the synchronizing device sears off the first shot, with the powder gases driving the bullet down the bore. The barrel and bolt remain locked together until the bullet clears.

The Hazelton device is located on the end and as soon as the bullet leaves the muzzle, it enters an orifice that is slightly larger than the bore. The gas that has been driving the bullet expands in the trap back of the orifice, and acts on the face of the barrel. It accelerates the rearward action, not only hastening unlocking but greatly speeding up the recoiling parts.

As the weapon's toggle joint is being broken to unlock, it exerts initial extraction on the empty case and loosens it in the chamber. By the time it unlocks, the cartridge case is free as the T-slot extractor carries it rearward. The T slot withdraws the incoming round from the belt and the bolt face is forced down by action of the side cams. When the recoiling parts reach the extreme rearward position, they encounter the modified buffer which returns the mechanism at high speed. As the bolt moves to battery, the live round is put into position for chambering and at the same time knocks the empty case free of the T slot through the opening beneath the receiver. In the last fraction of travel into battery the T slot is cammed up over the rim of the incoming round. The sear is released when the toggle locking joint advances beyond the center line. As long as the sear remains depressed, the cycle is repeated.

Following World War I, a vast number of Vickers aircraft machine guns were left in stock, but their manufacture had been such that the inter-changeability of parts could not be assured. They had been fabricated by many different companies under war conditions. With the let-down in ordnance development that followed the conflict the difficult task of overhauling these guns was undertaken, including the modification of certain parts to improve reliability and insure the ease of changing parts.

The guns, when completely gone over, were designated Mark V. It took from five to eight of the earlier models to make one of the improved versions. England finally wound up with a sizable quantity of the weapons and felt secure as far as aircraft armament was concerned until the decision was made to arm its future fighters with eight guns apiece. Then the director of equipment realize that the guns in storage would not last any time in the event of war.

The Vickers-Maxim guns on hand at the beginning of World War II included the outmoded class E of World War I vintage, and the class F observer's gun that fed from both drum and belt. Both weapons were in rifle caliber. In caliber .50 were the Mark C, a peculiarly designed weapon intended for use against armored vehicles and for antiaircraft work and the Mark D for antiaircraft use. The latter fired a high velocity projectile having a rate of 3,000 feet per second.

While these weapons were admittedly out of date, they were not replaced by better aircraft guns until after they had carried the Royal Air Force victoriously through the battle of Britain in a decisive struggle for air supremacy from the Allies' point of view.

Chapter 4
German Maxim-Type Aircraft Weapons

Early Adaptations

The German Government had prepared well For the inevitable conflict known as World War I. It decided early that machine guns would play a dominant role and concluded from secret tests that the Maxim machine gun, as it was still known in Germany, was the most reliable firing mechanism yet designed. The Model '08 Maxim was adopted as its first line machine gun. A later refinement to the standard '08 model resulted in a lighter version known as the '08/15. The water-cooled weapon was still fairly heavy and its 50-round belt with container could be attached on the side. A shoulder stock was also added together with a lightweight bipod of 2½ pounds. The total weight without water but with bipod was 31 pounds. The '08/15 differed from the '08 gun principally by its method of cooling. On this version the water jacket was simply filled and the jacket plug screwed in. There was no way to circulate the water as provided for in the heavier gun.

The weapon was produced in unusually great quantities as its modification from the original '08 model was comparatively easy. Allied intelligence agents estimated that at the outbreak of the war Germany had at least 12,500 Maxim-type guns stored in huge warehouses and 50,000 more on order. That the nation's existence was

Maxim Machine Gun, Model '08/15, 7.92 mm, German.

entrusted to this one type of machine-gun mechanism shows the extent of German confidence in the principles developed by an American, Hiram Stevens Maxim.

The '08 and '08/15 models were both used extensively in arming Zeppelins against hostile aircraft. The Germans felt that the tops of the dirigibles made unusually stable platforms from which to fire bursts of any length desired, thanks to the water cooling of the barrels. The lack of a critical weight factor with the Zeppelins allowed German airship commanders to install water-cooled Maxims both on the top gun platforms and along the sides of the gondolas.

As early as a year before the war, the German press publicized the remarkable successes scored by machine gunners firing from the decks of Zeppelins. Part of a story appearing in September 1913 is here quoted to show the confident attitude of the crews that manned the airships:

"As could be foreseen from the absolute stable nature of that gun platform and from the entire lack of vibration and swaying, these tests were almost as successful as they would have been had the machine been discharged from the top of a mountain. The writer speaks from experience having made tests in aiming from the window of the cabin of the Zeppelin in flight. . . . We can depend upon seeing cannon appear on the large dirigibles in strict accordance with this stage of development by the enemy just as we saw machine guns appear which are now ample protection against airplanes."

But with all their planning, the Germans did not foresee the incendiary bullet and its effects. The British shot the Zeppelin and its superior armament out of the sky by puncturing its huge hydrogen-filled envelopes with flaming bullets. In a few short months the reign of the much-dreaded airship ended.

Parabellum Machine Gun

The German Government a good many years prior to the war placed large orders for machine guns with its main arms-producing factory, the Deutsche Waffen- und Munitionsfabriken, located in Berlin. This company had unquestionably the greatest staff of gun experts to be found in any country. Its original head engineer had been an American, Hugo Borchard, the inventor of a pistol afterwards erroneously named for his assistant and successor, Georg Luger. Early in 1911 a gun designer, Karl Heinemann, joined the firm. He had already made a name for himself in the field of automatic weapons. Heinemann was given the all-important job of refining the Maxim gun. His resulting achievement was one of the most outstanding efforts to come from World War I. The German Army, committed to the Maxim gun which was already under production, specified the mechanism must be of this type. It requested a lightweight high-speed gun that would fire the same 7.9-mm Mauser cartridge as did its heavy machine guns and infantry rifle. To make a definite improvement on such a time- and battle-tested weapon required the utmost skill and Karl Heinemann proved equal to the occasion.

The product of his effort was labeled the "Parabellum," which was the code name of the D. W. M. plant when referred to in correspondence. This superb weapon, like so many of its contemporaries in other countries, did not attract the attention it deserved until the necessity of war gave it a place among the finest automatic firing mechanisms.

Heinemann made the toggle joint break up instead of down, as in the original Maxim. The return spring was placed centrally against the crank and stored energy during the recoil stroke. The act of feeding was performed by a pawl working off the lock instead of by vertical movement of the lock itself. A differential action was also incorporated to speed up feeding of the next to the indexed round. This was done by forcing the barrel forward by cams before the recoiling lock had reached its extreme travel rearward. A faster rate of fire was made possible by such utilization of the feed pawl. The feed belt was made of cloth or fabric wound on a spool fastened to the gun's receiver, thus allowing it to swing with the gun. In contrast with the earlier model the fusee spring was not adjustable.

This refinement by Karl Heinemann was the lightest Maxim-action gun ever designed. It weighed only 22 pounds without accessories, with a 700-round-a-minute rate of fire. Needless to say, it was the very thing the German Air Force

Parabellum Aircraft Machine Gun, Model 1913, 7.92 mm.
This Early Type Used the Water-Cooled Jacket Slotted for Air Cooling.

was looking for when its Zeppelin threat was exploded by British machine-gun fire. The Parabellum was the German first-line aircraft machine gun throughout the war. A few have also been found equipped with water jackets for ground use or perhaps more logically for Zeppelin mounting.

The following cycle of operation of Karl Heinemann's Parabellum, or refined Maxim gun, is given:

When the cartridge is fired, the whole inside portion travels backward with the breechblock still firmly locked to the barrel until the outside crank comes in contact with the resistance roller. The crank then begins to turn downward, carrying with it the connecting rod, the other end of which draws the breechblock away from the barrel.

The weapon has a sliding T slot that also recedes, with the live cartridge drawn from the belt and the empty case from the barrel. It is guided and supported by the projections extending side-wise from its upper end, which ride over the straight part of the side cam, riveted to the side

plates, until the cartridge just drawn out of the belt is clear of the feed way. Then the projections follow the downward-curved edge of these cams, guided from the top by an inversely curved cam, formed on the guide piece for the breechblock and riveted to the under side of the cover.

During this period the connecting rod in its downward movement presses against the tail of the tumbler, which, in its turn, draws back the firing pin and compresses the mainspring. The sear engages into a notch in the tumbler and the safety sear re-engages with a shoulder on the firing pin. When nearly at the end stroke of the breechblock, the T slot's projections leave the points of the side cams and the T slot drops into its bottom stop by its own gravity assisted by the guide directly above it.

This alines the cartridge with the chamber of the barrel, which pushes the empty case clear of the bolt face and through the slot in the bottom of the receiver. The crank, having now completed its rearward turn, begins its return stroke, and the advancing breechblock forces the live cartridge into the chamber.

In this operation the Parabellum's T slot is steadied, as its projections are kept in contact with the lower surface of the side cams. As the crank returns toward its horizontal position, projecting cams, or side levers of the connecting rod, come in contact with the ends of the lifting levers, pivoted to the breechblock and thereto by the pin. The other ends of these lifting levers are engaged between two lugs on the carrier. When they are pivoted by leverage of the cams on the connecting rod, the carrier rises with a steadily increasing velocity and the lower part of the upper stop slides over the head of the live cartridge in the chamber. At the same time the upper part of the T slot slips over a fresh cartridge in the feed way and retains it in position between the grooves of the T slot and the upper and lower parts of the stop.

When the T slot arrives at the top, the end of a leaf spring, riveted to the right-hand recoil plate, drops into a notch cut on its side and keeps it in that position until, in its rearward travel, the projections slide onto the side cams and support it.

The crank and connecting rod, having resumed their firing position, brace the breechblock hard against the breech. At the last moment the connecting rod lifts the safety sear. The effort of the mainspring is thrown upon the hand sear. If now the trigger bar at the bottom of the gun casing is held to the rear by continued pressure on the trigger connected thereto, the tail of the sear will strike against the lug at the free end of this bar and set free the firing pin, the point of which will pass through its tunnel in the bolt face and explode the primer. The cycle described will continue as long as the trigger is kept depressed.

The Fokker Synchronizer

Since the action of the Parabellum was front seared, it was ideal for synchronizing when employed as an observer's gun. It was used in such a manner after Antony H. G. Fokker, the famed aircraft designer, developed a mechanical method of firing safely through the propeller blades.

He conceived his idea when shown the crude arrangement of a French plane that had been shot down when attempting to fire through the air screw. Bringing his inventive genius to play after examining the enemy device, Fokker produced an interrupter gear. While he was acclaimed for his feat, his invention was actually based on a patent issued in 1913 to Franz Schneider, a Swiss aeronautical engineer, who had offered his invention to the German Army as early as 1912. After examination, it had been rejected as unnecessary, since there was no possibility that the airplane would ever become a fighting machine. At the time the Zeppelin so dominated the German mind as the perfect aerial weapon that the value of Schneider's patent could not be foreseen. It was only in an hour of desperation that Germany was provided with Fokker's version of the Schneider synchronizer.

Antony Fokker was born in Batavia, Java, in 1890 and at an early age showed a genius for invention. This brilliant Netherlander was already an experienced aviator and airplane designer when World War I broke out. He had previously offered his designing talents to his own country, then to France and to Britain, only to be ignored by each. Germany accepted his services at once and the resulting relationship came within a hairbreadth of costing the Allies the war.

Parabellum Aircraft Machine Gun, Model 1913, 7.92 mm, with Refined Barrel Jacket.

England. which had paid no attention to the "young fanatic," later secretly offered him £2,000,000 for his services.

It is hard to believe that this man who gave Germany domination of the air for 6 months was barely 24 years old at the time. The act that accomplished it was but incidental to his really notable work in the design and construction of the Fokker fighter planes. Within 48 hours after examining the makeshift French device, he produced a reliable interrupter gear based on Schneider's patents. It added a hundredfold to the deadliness of the superb fighting craft of his own design. The fact that he had never handled a machine gun before in his life made his feat even more astounding. The German staff was highly incredulous that he could turn out anything worthwhile in such a short time, and Fokker gained its confidence only by repeated demonstrations with a motor on the ground.

The first German pilot to use the synchronizer against the enemy was Lt. Oswald Boelke, later to become Germany's pioneer ace in great part because of this device. The next flyer to install one on his plane was Lt. Max Immelmann, also destined to become a great air fighter. After hesitation in the beginning, the General Staff became wildly enthusiastic about the new weapon. They had a right to be as the synchronizer gave them a superiority that took many months for the Allies to overcome.

While there was great similarity between the German and the later British mechanical firing devices, except the Constantinesco type, the Beret of the Fokker-Schneider system was that the interrupter gear kept the trigger depressed while the propeller arc was clear. It let up on the sear at the approach of the leading edge of the blade which acted as an interrupter only in a burst. The British device worked just the opposite in that it tried to release the sear by a series of lugs striking cams. This allowed bullets to hit the blade if anything worked loose or if. anything happened to change the timing of the weapon, since each individual impulse fired a shot. The German synchronizer fired a continuous burst except when the approach of the propeller and its corresponding lug on the shaft interrupted fire until the trailing edge of the blade had cleared.

The German fighting plane's propeller in normal flight rotated 1,200 times per minute, and as this made the blades pass a given place 2,400 times, it can readily be understood that the timing device must be foolproof in design. With a 6-inch space passing a given point 2,400 times a minute, the fundamental fact underlying the successful operation of any synchronizer is the relatively greater velocity with which the bullet is traveling to that of the turning blade.

The first Fokker planes, the E1, E2, and E3, equipped with the Dutch inventor's interrupter gear, appeared on the Western Front in December 1915. They gave the Allies a decided setback and caused many casualties until something as efficient was produced as a countermeasure. The Fokker fire interrupter was one of the German Air Force's top secrets, although in April 1914 Franz Schneider not only had allowed the New York publication, the Scientific American , to print an article describing the device, but had furnished drawings showing its construction. The Allies, however, did not realize its value until much later.

Maxim Machine Gun, Model 08/15, 7.92 mm, Modified for Synchronizing.
This Weapon Manufactured at the Spandau Arsenal is Often Called the Spandau Machine Gun.

In connection with the first test of the synchronizer, the following graphic story is told in Fokker's own words:

"While I was flying around about 6,000 feet high, a Farman two-seater biplane, similar to the ones which had bombed me, appeared out of a cloud two or three thousand feet below. That was my opportunity to show what the gun would do, and I dived rapidly toward it. The plane, an observation type with propeller in the rear, was flying leisurely along. It may even have been that the Frenchman didn't see me. It takes long practice and constant vigilance to guard against surprise air attack, for the enemy can assail one from any point in the sphere.

"Even though they had seen me, they would have no reason to fear bullets through my propeller. While approaching, I thought of what a deadly accurate stream of lead I could send into the plane. It would be just like shooting a rabbit on the sit, because the pilot just couldn't shoot back through his pusher propeller at me.

"As the distance between us narrowed, the plane grew larger in my sights. My imagination could vision my. shots puncturing the gasoline tanks in front of the engine. The tank would catch fire. Even if my bullets failed to kill the pilot and the observer, the ship would fall down in flames. I had my finger on the trigger. . . . I had no personal animosity toward the French; I was flying merely to prove that a certain mechanism I had invented would work. By this time I was near enough to open fire and the French pilots were watching me curiously, wondering, no doubt, why I was flying up behind them. In a moment it would be all over for them.

"Suddenly I decided that the whole job could go to hell. It was too much like 'cold meat' to suit me. I had no stomach for the whole business, nor any wish to kill Frenchmen for Germans. Let them do their own killing!"

Introduction of Armored Planes

In 1917 the Gotha Waggonfabrik Co. designed and built for the German Air Force a battle plane that had great influence on future machine-gun design. This aircraft was known as the Gotha biplane, a huge affair with a wing span of 78 feet and an over-all length of 41 feet. The motors were encased in nacelles resting in the lower wing. It was a three-seater, with space for two observer gunners and a pilot. The armament consisted of three machine guns, two Parabellums and a water-cooled Maxim. The latter was mounted in an ingenious tunnel under the aft part of the fuselage so that the rear gunner could fire with an unobstructed view below and to the rear of the machine.

Having great lifting power and with weight not being a critical factor, the Gotha had armor placed over vital parts in the engine and around crew members. The unusual fire power, armor and absence of unprotected blind spots made it a formidable foe to encounter. The Allies lost many pilots who tried to attack the ship from

beneath only to be cut down by the concealed gunner, using a water-cooled gun that permitted bursts of any necessary length.

Quentin Roosevelt, an American pilot and son of ex-President Theodore Roosevelt, was killed while attacking one of these Gotha planes from below. Witnesses of the fight saw many of Roosevelt's tracers hit the Gotha only to bounce harmlessly off the armor. The young pilot's death and the impotency of his guns made our ordnance officers realize something had to be done at once to overcome this tremendous advantage.

The caliber .30 was definitely outmoded from then on. The first thing done was to use the principle of Thorsten Nordenfelt and produce an armor-piercing bullet. The next was to demand the design of a larger caliber higher velocity cartridge and a machine gun to fire it. The Gotha battle plane was the first incentive for larger bore guns. It was only a few days after Quentin Roosevelt's death that Gen. J. J. Pershing cabled our Ordnance Department giving minimum specifications that he considered necessary for an adequate machine gun. In this correspondence he stated that the velocity should not be under 2,750 feet per second and the caliber be a minimum of one-half inch. While the passing years have proved the general's wisdom, it was the German Gotha biplane which showed to all concerned that the day was over when an infantry type machine gun could bring to earth a military fighting ship.

The T. u. F. Machine Gun

The Germans, being the first to armor their own planes, knew that by doing so their existing rifle-caliber machine guns likewise would be made obsolete for aircraft use. They proceeded with typical thoroughness to prepare for the day when their airmen would have to contend with armor on enemy planes. This vital need for a machine gun firing a bullet large enough and with enough velocity to penetrate heavy armor was brought to their attention in a more forceful way by the British use in 1917 of heavy armored motor-propelled land vehicles called tanks.

To combat this new weapon, the Germans quickly scaled up their 7.9-mm infantry rifle cartridge to 12.7 millimeters, having a 770-grain boat-tailed bullet with a muzzle velocity of 2,650 feet per second. When a tungsten steel core was used, to their agreeable surprise it penetrated the sides of captured British and French tanks easily at 100 yards. The armor was in some places as much as one and a fifth inches in thickness. The newly designed cartridges were then being fired in a clumsy bolt-action single-shot rifle, employed through desperation as an antitank weapon. It was realized that, if an automatic firing mechanism could be produced capable of handling the new ammunition, the British advantage from the use of armored tanks would be quickly overcome.

As the Maxim Model '08 caliber 7.9-mm machine gun was Germany's main standby in its highly efficient automatic weapon units, and as the German ordnance designers had seen the identical mechanism used in a shell gun of 37-mm bore, called the "pom-pom," the most logical solution for the problem seemed to be the designing of a Maxim action between these two extremes that would successfully handle the high-velocity 12.7-mm antitank rifle cartridge. In early 1918 this was done in great secrecy and with a manufacturing priority second only to that of the high cyclic rate Gast aircraft machine gun. The latter weapon was counted on to give the nation air superiority.

The German high command felt that the large caliber machine gun would simply annihilate the armored units of the enemy both on the ground and in the air. Consequently they named their new and deadly devisement the "T. u. F." (Tank und Flieger , meaning Tank and aircraft ) machine gun. The intended use was clear from its name. But regardless of the excellence of the idea, the fabrication of components did not reach a stage where it ever saw action against the enemy. There were 4,000 T. u. F. machine guns on the point of delivery when the Armistice was signed.

With the coming of the army of occupation, the German Army's ordnance section, which supposedly did not exist, according to the Versailles treaty, but was nevertheless highly active, or-

Maxim Machine Gun, Model '08/15, 7.92 mm, Modified for Aircraft Installation.

dered that the weapons be hidden and that all correspondence concerning them be done in code.

Two of the code designations given the weapon were "Machine gun 08" and "SS machine gun." The Germans believed that the Allied intelligence had knowledge of the development of a super antitank and aircraft machine gun, but felt the weapons could be concealed since none had ever been on a battlefront. The designation "Machine gun 08" was used to create confusion with the ordinary 7.92-mm infantry-type machine gun. During the war numerous model '08 Maxims were altered to take a Schwere cartridge having a slightly different shaped bullet, and these guns were marked with a large letter "S" on top of the receiver to show modification. The Maxims so labeled were known in an unofficial way as the "S" machine guns. The Germans hoped that the addition of a second "S" in their code for the T. u. F. would obscure its existence.

Photographing of the gun and its movement to storage without first being covered were not permitted. However, an Allied commission sent into Germany not only learned of the existence of the weapons but also seized all correspondence between the underground German ordnance group and the companies that manufactured and assembled the components. They found beside the 4,000 originally promised for fall delivery that an additional 2,000 had been ordered as late as October 1918. Thus the German Army expected to have on hand 6,000 such weapons to meet the well-advertised Allied spring offensive that the Armistice canceled.

The T. u. F. was made up of 250 components, manufactured by 60 different companies. These parts were delivered to the Maschinenfabrik Augsburg-Nuremburg, which was especially charged with assembling and mounting the weapon. All steel used in this high priority work was delivered exclusively by the Siegen-Solingen-Gusstahl A. V., located in Solingen.

The Germans succeeded, after finding that the Allies had possession of all facts concerning the gun, in destroying practically all assembled ones and it was with the greatest difficulty that ordnance men of the United States Army in August 1921 finally located a T. u. F. with 82 cartridges. This gun, along with the small amount of ammunition, was eventually shipped to Springfield Armory for test. There being only the few cartridges available at the time, no conclusion as to its merit could be reached. Besides, there was under development by Colt's Patent Firearms Co., of New Haven, a caliber .50 machine gun that was considered by all to be a genuine improvement on the German version. The cartridge used by the American gun, however, was later copied from the one fired by the T. u. F., it having better ballistic characteristics than the one being developed in this country.

The unusually high regard the German authorities had for the weapon is shown by the following: Even after practically all of the supply had been destroyed, as a result of the Inter-Allied Control Commission's discovery, the

outlawed German ordnance authorities notified by telephone the 60 plants previously engaged in making the components not to stop fabrication of these parts. A written order was later found that guaranteed payment to the companies for the finished parts even if they were seized by the Allied occupation forces, and that directed them to "continue to manufacture them at all costs." The Allies in due time stopped all production on the gun in Germany but it took several years to accomplish it.

In 1923 it was reported to the United States Army Ordnance Department that German patents had been granted on the design of the T. u. F., which had been sold to Czechoslovakia by-Mr. A. Ten Bosch, a civil engineer of the Hague, Holland, to whom they had been assigned. Ten Bosch had retained the rights for production of the weapon in the United States, but the Army was not interested.

Models of Maxim Guns

At the conclusion of the discussion of Maxim-type weapons in this publication, a tabulation is given, for ready reference, of the various Maxim systems and models used by the nations of the world:

System	Country	Designation	Bore
Vickers	Holland	Model 1918	7.92 mm
Maxim	Germany	Model 1899	7.92 mm
Maxim	Germany	Model 1901	7.92 mm
Maxim	Germany	Model 1908	7.92 mm
Maxim	Germany	Mod. '08/15	7.92 mm
Maxim	Germany	Mod. '08/18	7.92 mm
Parabellum	Germany	Model 1914	7.92 mm
Parabellum	Germany	Model '14/17	7.92 mm
Maxim T. u. F.	Germany	Model 1918	13 mm
Maxim DWM	Germany	(circa 1902)	37 mm
Maxim	United States	Model 1904	cal. .30
Vickers	United States	Model 1915	cal. .30
Vickers AVN	United States	Model 1918	cal. .30
Vickers AVN	United States	Model 1918	11 mm
Vickers AVN	Japan Navy	Type 97	7.7 mm
Vickers AVN	Japan Army	Type 89	7.7 mm
Vickers	Japan	Type 98	7.7 mm
Vickers A. A.	Japan	Model 17, Type 1	40 mm
Maxim (captured)	Greece	German type	7.95 mm
Vickers TNK	Greece	British type	7.9 mm
Maxim	Austria-Hungary	Model 1889	8 mm
Maxim	Austria-Hungary	Mod. '89/04	8 mm
Maxim (F. N.)	Belgium	Model 1911	7.65 mm
Maxim1	Belgium	Model 1908	7.65 mm
Maxim1	Belgium	Mod. '08/15	7.65 mm
Vickers AVN	France	British type	7.7 mm
Vickers AVN	France	British type	11 mm
Vickers	France	Model 1909	7.7 mm

¹ Converted German.

System	Country	Designation	Bore
Vickers	France	Model 1909	8 mm
Maxim (ex-German)	Poland	Mod. '08	7.92 mm
	Poland	Mod. '08/15	7.92 mm
Maxim	Chile	Model 1902	7.92 mm
Maxim	China	Model 1935	7.92 mm
Maxim	Italy	Model 1906	6.5 mm
Vickers-Maxim	Italy	Model 1911	6.5 mm
Maxim	Peru	Model 1901	cal. .301
Maxim	Peru	Model 1911	cal. .301
Maxim	Great Britain	(circa 1891)	cal. .45 (Martini-Henry)
Maxim	Great Britain	(circa 1893)	cal. .303
Maxim	Great Britain	(circa 1899)	cal. .303
Maxim conv. Mk I	Great Britain	(circa 1902)	cal. .303
Maxim conv. Mk II	Great Britain	(circa 1898)	37 mm
Vickers	Great Britain	Mark I (circa 1912)	cal. .3032
Vickers	Great Britain	Mark I	cal. .3033
Vickers TNK	Great Britain	Mark VII	cal. .303
Vickers TNK	Great Britain	Mark IVa	cal. .303
Vickers TNK	Great Britain	Mark IVb	cal 303
Vickers TNK	Great Britain	Mark VI	cal. .303
Vickers TNK	Great Britain	Mark VI*	cal 303
Vickers AVN	Great Britain	Mark II	cal. .303
Vickers AVN	Great Britain	Mark IIa	cal. .303
Vickers AVN	Great Britain	Mark III	cal. .303
Vickers AVN	Great Britain	Mark V (rebuilt from Mk IIa and III.)	cal. .303
Vickers AVN	Great Britain	Mark VI (new mfg.)	cal. .303
Vickers AVN	Great Britain	Mark VI* (converted circulator)	cal. .303
Vickers AVN	Great Britain	Mark VII (new mfg.)	cal. .303
Vickers TNK	Great Britain	Mark I	cal. .50
Vickers TNK	Great Britain	Mark II	cal. .50
Vickers TNK	Great Britain	Mark IVa (converted Mk I)	cal. .50
Vickers TNK	Great Britain	Mark IVb (converted Mk I)	cal. .50
Vickers TNK	Great Britain	Mark V	cal. .50
Vickers Naval	Great Britain	Mark II	cal 50
Vickers	Portugal	Model 1917	7.7 mm

² Ground.

³ Air, converted from ground.

System	Country	Designation	Bore
Vickers	Portugal	Model 1930	7.7 mm
Vickers	Portugal	Model 1937	7.92 mm
Maxim	Switzerland	Model 1894	7.45 mm
Maxim	Switzerland	Model 1900	7.45 mm
Maxim	Switzerland	Model 1911	7.45 mm
Vickers AVN	Czechoslovakia	British type	7.92 mm
Maxim (former German)	Turkey	Model 1908	7.92 mm
	Turkey	Mod. '08/15	7.92 mm
Vickers	Turkey	British type	7.92 mm
Maxim (former German)	Lithuania	Model 1908	7.92 mm
Maxim	Estonia	German type	7.7 mm
Maxim	Finland	Model 1932	7.62 mm
Maxim	Russia	Model 1905	7.62 mm
Maxim	Russia	Model 1910	7.62 mm
Maxim Tokarov	Russia	(circa 1924)	7.62 mm
Maxim Kolesnikov	Russia	(circa 1924)	7.62 mm
Vickers	Bulgaria	British type	7.7 mm
Maxim	Serbia	Model 1909	7 mm
Maxim	Bulgaria	Model 1909	8 mm
Maxim	Yugoslavia	Model M8M4	7.92 mm

⁴ Converted spoils of war. Serbian and Bulgarian Model 1909 Maxim, 7 and 8 mm, respectively, both changed to 7.92 mm.

Chapter 5
Marlin Aircraft Machine Gun

The mounting of Browning-designed machine guns in aircraft dates back to the Colt-Browning model, nicknamed the "Potato Digger" by the infantry because the operating lever after each shot swung down in pendulum fashion underneath the barrel. Due to a scarcity of machine guns, a few of these were placed in French and British pusher-type planes during the early stages of World War I. When this country entered the conflict, there was desperate need for any kind of machine gun. The type that could be mounted readily in aircraft without demanding too much of the already limited space or requiring any protruding accessories was especially in demand. While the swinging lever of the '95 model gun had the advantage of giving smoother action and exceptional reliability in ground operation, it was found to be very much in the way for aerial firing.

Carl G. Swebilius.

The Marlin-Rockwell Corp., New Haven, Conn., which had been given the contract to produce many thousands of the Colt-Browning '95 model for infantry use, undertook to remedy the situation and make the weapon acceptable for aircraft use. Marlin was no new name in the gun manufacturing business. In 1870, the founder, J. M. Marlin, began making single-shot pistols and revolvers under the Ballard patents in a small New Haven shop. Later he brought out the J. M. Marlin-Ballard single-shot rifle that became one of the world's outstanding target arms because of its simple strong action and deep Ballard rifling. In 1880 Marlin himself designed a repeating lever action rifle that has been a specialty of the plant ever since.

Ten years later the Marlin Firearms Co. introduced a silent side-ejection big game rifle that was a notable contribution to safety and convenience. This lever-action magazine repeating arm created a sensation. Sturdy yet light, it was amazingly simple and practical in design and a reliable, accurate repeater.

In 1915 the firm was taken over by the Marlin-Rockwell Corp., which was established in New Haven for the production of machine guns on a vast scale. Carl G. Swebilius was placed in charge of experimental work. The Swedish-born Swebilius came to America in 1896 at the age of 16, taking a position with the Marlin Co. Beginning as a gun-barrel driller, he soon became one of the outstanding American firearm designers.

in World War I, Swebilius modified the Colt-Browning gun by doing away with the lever and substituting a straight-line gas-actuated piston. Such a change presented problems of its own. instead of giving a slow and gradually accelerated backward thrust through a connecting rod arrangement, as in the case of the lever-operated weapon, the piston was driven back hard at the very beginning of its stroke. This caused a loss of initial extraction and resulted more often than not in tearing off the cartridge head instead of extracting the empty case. The fault was soon

remedied by further modifying the action through the addition of greater weight to the piston. The first rearward movement of the bolt was thereby somewhat retarded.

Swebilius deserves great credit for accomplishing this most difficult task, especially since it was performed in a few weeks' time. In this short period he made the Marlin gun a reliable automatic arm that was used throughout the war and for 3 years afterwards as the principal synchronized automatic machine gun of the American air force. Later it was also adapted to tank use. The weapon met with considerable enthusiasm on the western front as the following cablegram from A.E.F. headquarters in February 1918 shows: "Marlin aircraft guns have been fired successfully on four trips from 13,000 to 15,000 feet altitudes at a temperature of -20 degrees Fahrenheit. On one trip guns completely covered with ice. Both metallic links and fabric belts proved satisfactory."

Development of the Marlin aircraft gun was primarily one of modification and refinement from the gas swinging lever Colt '95 model. Marlin was so successful in the undertaking that new features were constantly being added. On 1 January 1918, the Signal Corps requested the design of a different firing mechanism that would permit single or automatic shots when used with four-bladed propellers and with the new and improved Nelson mechanical synchronizing gear. An arrangement whereby the hydraulic and mechanical trigger motors could be attached to the front of the lock container was also desired. The lock container was to be redesigned and the hammer materially lightened to increase the rate of fire.

An informal test was held on 27 December 1917, at which time another type of hydraulic synchronizing gear, also manufactured by the Marlin-Rockwell Corp. and similar to the Constantinesco gear, was tried out at rates varying from 200 to 600 rounds per minute with a total angle of dispersion of 63°. It was the closest and most accurate synchronization accomplished in this country with any type of machine gun so far. The Marlin aircraft machine gun has the distinction of being the first gas-operated weapon to be synchronized successfully.

The arm employed either a fabric or a disintegrating metal link belt that could be made up with as many as 500 rounds. Actually metallic links were generally used in aircraft throughout the war because of the inconvenience of disposing of the fabric belt's loose end after firing.

On 8 January 1918, a conference was held by the Army Ordnance Department at New Haven to decide on changes to be incorporated in the firing mechanism. Both the Signal Corps and the Marlin-Rockwell Corp. submitted new designs. Tests in the last days of that month proved the Marlin-Rockwell device satisfactory and the Signal Corps design a total failure because of easy breakage of parts. This was accountable for both by inferior material and by generally poor construction. A new hydraulic trigger motor was adopted at the same time and a contract for 15,000 motors and modified firing mechanisms was placed with Marlin-Rockwell. By this time the alteration and redesign of so many parts meant that they were not interchangeable with similar components of the old guns. To distinguish it in nomenclature from its original parts,

Marlin Aircraft Machine Gun, Model 1917, Cal. .30.

the improved product was called the Marlin Aircraft Machine Gun, Model 1918.

The modified weapon's principal point of difference from the 1917 model lay basically in its ability to be adapted to fire single shot or full automatic. This permitted much closer synchronization than full automatic alone. At the conventional propeller speeds of the day, however, the rate of fire was almost as great as with the automatic principle.

One of its main points of difference from the components of the 1917 model was a reduced gas pressure in order to cut down the parts breakages and stoppages caused by recoil. It was accomplished by enlarging the size of the gas piston and by drilling out less of the gas adjuster screw. The latter increased the volume of expansion of the gas chamber in the cylinder and cushioned its action. By milling three slots about one sixteenth of an inch in diameter through the side of the gas adjuster barrel, a vent was provided for the gas in the cylinder. It could be opened or closed at will by means of the adjuster. The double purpose was thus achieved of satisfactorily cushioning the recoil and also affording a wide range of adjustment of gas pressure acting on the piston. The increased recoil power necessitated a change in the bolt's cam slot pin to eliminate excessive breakage. More stock was added to the rear end of this piece to strengthen the cross section at a point where fracture was most frequent.

The fin was also given a glass-hard treatment followed by spot annealing. Material of the bolt pin was changed to chrome nickel steel to increase its durability as breakage often resulted from the severe wear on it after the first few hundred rounds. The newly designed and more powerful hammer action also proved too strenuous for the firing pin assembly and the pin had to be redesigned with a long gradual taper throughout its entire length. This made it not only stronger but at the same time more flexible.

In order to eliminate accidental firing by contact of the firing pin with the extractor, a three sixteenth inch piece of stock was added at the top of the latter's lug employed to support the front of the bolt. It was also found necessary to bevel off the end of the receiver on the left hand side directly behind the ammunition belt. Interference at this point with the base of the cartridge had a tendency to twist the belt and cause stoppage. A hole was drilled through the right side of the lock container in which a key, known as the functioning operating cam, was inserted. Rotation of this key raised the trigger, thus enabling the gun to fire full automatic for testing and firing without the synchronizing gear.

An interesting device added to the new Marlin was known as the jam preventer. It consisted of a small steel stamping which was applied without further alteration to the ratchet lever in place of the ratchet lever pin washer. Its function was to prevent the lever's pawl from engaging the feed wheel when the cartridge was in the act of feeding and thus blocking the stop against further rotation of the wheel. The device would have been more appropriately named an anti-double-feeding device. According to reports from the field a reduction of stoppages resulted from use of the jam preventer. Unloading of the gun could also be accomplished by this arrangement without removing the belt as was heretofore found to be necessary.

Marlin Aircraft Machine Gun, Model 1918, Cal. .30.

One more improved feature was the placement of the trigger motor at the forward end of the lock container and connecting it with the trigger by means of a timing gear. With this attachment the bolt could be removed without dismounting the trigger motor and carrier as was necessary with the 1917 model.

The gun's wide range of gas adjustments made it very dependable and it would fire positively under the most extreme conditions. Although originally adopted as a temporary substitute, the gun was improved by continued effort to such a highly satisfactory degree as to be pronounced the equal of the Vickers and other aircraft machine guns in excellence, synchronization and general reliability. Its success overseas was phenomenal. It was enthusiastically received by both the A.E.F. and the French as soon as pilots had mastered its few idiosyncrasies. The following reports bear witness to its competence.

"Pershing. 810-2. 3-29-18. Further test Marlin guns with both flexible and synchronized mounting made at 20,000 feet altitude, temperature below zero. Both guns functioned perfectly throughout the test."

"Pershing. 859-6. 4-12-18. Nine flights made to date with Marlin machine guns at altitudes ranging from 10,000 to 20,000 feet. Temperatures ranging from zero to well below zero Fahrenheit. Total rounds fired 1700. Guns used on both standard fixed and improvised flexible mounts. Both metallic and fabric belts used. No difficulties encountered and no stoppages. Recommend shipment of this gun continued rapidly as possible."

Various aerial squadrons added their praise with such words as the following: "In fact, all pilots have expressed a decided preference for the Marlin, as they shoot faster than the Vickers and are easily cleared of feed troubles." "The four Marlins we are using have kept up their perfect record." And "Thus far no Marlin guns have jammed in the air and they are in high favor among all pilots."

A report from the Chief Ordnance Officer of the A. E. F., dated 23 November 1918, stated that 22 squadrons at the front were either partially or fully equipped with Marlins having both hydraulic synchronizing gear and mechanical synchronizing gear. They gave thorough satisfaction, being used on various planes such as the U.S. D-4, Spad 8, Spad 7, Salmson, and Breguet observation planes. Some difficulty was encountered in adapting the Marlin to planes bought from the French and British Governments since the fittings of these planes already had feeding arrangements intended for caliber .303 Vickers. But this trouble was soon overcome and in August 1918 the first squadron of French planes equipped with Marlin guns arrived at the front.

The last gun of this type made, which was the thirty-eight thousandth, was taken from the assembly line and subjected to an endurance test of 10,000 rounds without a single stoppage or malfunction. At the end of the test it was found that only the replacement of a cracked shell extractor was necessary. There had been no appreciable increase in headspace and the condition of the gun after this firing was apparently as good as at the beginning. It passed inspection and was shipped as a new gun.

The first large shipment of 2,000 was sent to France on 11 October 1918, one month exactly before the end of the war, but it was not received in time for use at the front. The development of the Marlin as a flexible gun was also undertaken with promising success. The war was over, however, before much could be done with this type of gun.

All model 1918 Marlin aircraft guns were supplied with a trigger motor attached to the lock container, adapted for connections with both the Nelson and the C. C. synchronizing gear. The trigger motor, consisting of a piston and spring, was contained in a bronze cylinder which was screwed into the forward end of the lock container. The cylinder was provided with a coupling nut and tube into which the main pipe leading from the synchronizer could be soldered. A small vent screw located on top of this cylinder allowed the release of air from the system by bleeding. The C. C. synchronizing trigger motor was very similar to that used with the model 1917 aircraft gun.

These weapons also had electric heaters in order to prevent oil gumming up at the low temperatures accompanying extreme altitudes. The heaters were developed for both models of the Marlin aircraft machine gun. Each unit consisted of a resistance grid surrounded by insulat-

Marlin Tank Machine Gun, Model 1918, Cal. .30.

ing material and was riveted to the inside of the gun's bottom plate. It was connected with a bayonet plug on the under side of the bottom plate providing connection with the leads. The heater consumed 60 watts at 12 volts and was fed from the generator supplying the plane's lighting and heating system.

The Marlin gun, as issued, was belt fed, gas operated, and air cooled. It had a weight of 22½ pounds and without any speeding-up accessories normally fired 630 shots a minute.

To place the weapon in operation, a brass tip of the loading belt usually containing 250 rounds is inserted through the belt opening in the leftside plate and the first cartridge is forced up into position on the feed wheel. By pulling the charging handle lever twice to the rear, the cartridges are forced first into the feedway and then into the chamber. The gun is now ready for firing. When the trigger motor releases the sear, the nose of the trigger is disengaged and the hammer forced forward by the spring tension, striking the firing pin and firing the piece.

When the bullet passes the gas port near the muzzle on the barrel, a small portion of the live powder gas goes through the port and through a corresponding aperture in the gas chamber. There it strikes the piston forcing it to the rear and compressing the action spring. The spring then furnishes power for the forward movement. The lug on the slide strikes the feed lever forcing it to the rear. A pin located on the lever operates in the cam slot of the ratchet lever to force it upward, while the ratchet lever pawl becomes engaged in the feed wheel. As the slide which is fastened to the piston rod moves to the rear, it carries with it the bolt and extractor. The extractor claw withdraws a cartridge from the belt and places it on the carrier for chambering. The bolt pin working in the cam slot underneath the bolt forces its aft end upward and unlocks the piece. As the recoiling parts go to the rear, the

Marlin Ground Machine Gun, Cal. .30.

empty shell is pulled from the chamber by the extractor.

The base of the cartridge case during this movement strikes the shoulder of the ejector, and it is thrown out of the ejection slot on the right side of the receiver. The bolt on its continued backward motion strikes the hammer and forces it upward, compressing the strong hammer spring. The hammer then rides on the bolt for the balance of the recoil movement which ends as the slide strikes the springs on the buffer block. At this point counterrecoil movement begins, actuated by the force of the compressed action spring. The slide starts to move forward carrying the bolt with it. The cam on the bottom of the slide working against the carrier dog forces the carrier upward and alines the cartridge in front of the bolt. Continued movement forward then positions the round in the chamber.

As the bolt locks securely, the extractor cams itself over the rim of the cartridge case. At the same time the lug on the slide strikes the feed lever forcing it forward. During this final movement the feed lever pin working in the cam slot in the ratchet lever forces it downward. As a result the ratchet lever pawl turns the feed wheel. This action places the incoming cartridge in position to be engaged by the extractor.

The extractor claw then takes its position over the rim of the cartridge in the belt. Just before the bolt drops into the locked position, the hammer engages in the sear and trigger notch, provided the sear is not depressed. If the trigger is held down, the cam cut on the slide works on its corresponding lug on the firing mechanism forcing it out of engagement. This frees the sear from its notch and allows the hammer to strike the firing pin which discharges the cartridge. The cycle of operation continues until the trigger is released or the ammunition is exhausted.

If the trigger is released before all the cartridges have been fired, the bolt closes over a shell in the chamber but the hammer does not go forward. If the trigger is held down until the ammunition is exhausted, the bolt closes over an empty chamber.

The total number of the 1918 model Marlins manufactured was 15,000, as compared with 23,000 of the 1917 model. Conclusion as to whether the Marlin 1918 model machine gun was the U.S. Army's first line aviation weapon in World War I can be drawn from the report of a board of officers convened in 1920 by the War Department. The board was to meet as often as necessary for the purpose of considering the development of aircraft machine guns and aircraft cannon. The meetings took place regularly over a period of years until 1925 when it made its final report from which the following is quoted:

"The Board recommends that the Marlin machine gun, model of 1918, be continued in service, but that no further steps to improve the development of the gun itself be undertaken, in view of the present state of its development and a desire on the part of the Board to have all funds available for development work expended on the Browning aircraft machine gun.

"It is further believed that this gun is a

satisfactory air service weapon, although its limitations are acknowledged. It is not so efficient as to ease of assembly. Its clearances are smaller. It is more sensitive to dirt and rust than other guns examined by the Board. And it must be removed from its mountings for the purpose of cleaning and repairing in the airdromes. It is made to function with the Nelson mechanical gear and aside from the Browning aircraft machine gun no other machine guns have been made with that end in view. And these are the only two weapons now in the possession of the United States which as issued will so function. The question therefore solves itself, as the Marlin aircraft machine gun, model of 1918, is the only gun at present which can be issued to function with the Nelson gear. In the event that a more satisfactory type of gun passes successful tests and is accepted by the Air Service as a satisfactory machine gun for their use, upon completion of the redesign and tests now in progress it is recommended that these Marlin models of 1918 be withdrawn from service and held in reserve for emergency use only."

Chapter 6
Browning Aircraft Machine Guns

First Attempts at Air Firing

The caliber .30 Browning aircraft machine gun, which was designated the Model 1918, did not see combat service during World War I. The reason was that the poor choice of metals used in its construction and the demand for a high rate of fire caused the front lower part of the receiver to spread after comparatively few bursts and become unserviceable. The fault was ordered remedied by the addition of a stirrup at the affected part to give greater strength. As the Armistice followed shortly after delivery of the first guns, this failure and its subsequent correction seemed of small importance at the time.

Following the war the Army, which was charged with development of this weapon, set about to make the necessary modifications. Since there was no longer the critical time factor of the war years, the matter was closely studied. In order to produce a machine gun that would be adequate for years to come, many changes were found to be necessary. Some of the modifications were trivial, while others were so costly that it was sometimes felt the designing of a completely new weapon would have been more economical.

For like all aircraft machine guns it too evolved from a ground gun with one part changed, another lightened, and so on until the numerous alterations fitted the circumstances at

Browning Aircraft Machine Gun Mounted on a Bristol Fighter in England for First Test of the Browning in the Air.

hand. Then if the devisement did work, an increased rate of fire was demanded. This last feature almost invariably brought disaster to the successor of a once reliable, slow-firing, water-cooled, easily serviced gun.

This most certainly was true as far as the first Browning aircraft machine gun was concerned, as it had the same basic principles of the heavier infantry model lightened on a drawing board until it met a theoretical requirement.

Since a major overhaul was imminent, it was wisely concluded that all possible corrections should be made at the same time. As a result an Aircraft Armament Board was formed in 1920 and given power to make any changes thought necessary to meet future requirements. The report made by this board on the Browning guns tells in no uncertain manner all the modifications needed, along with what was considered desirable in the larger caliber aircraft machine guns that soon should be making their appearance.

The general report of the Aircraft Armament Board which convened to study the aviation ordnance question gives a most graphic description of the existing state of affairs. It first met on 29 March 1920, and after numerous sessions made its final report 5 years later. Its section on the Browning aircraft guns is here extensively quoted.

(It is hard to believe that 2 years after World War I the United States air force had no machine gun suitable for combat save the modified Colt '95 model gun, known as the Marlin Aircraft Machine Gun, Model 1917-18. Attention is invited to the number of new parts that had be to added and old ones reworked on the short-recoil-operated weapon Model 1918 before it was considered serviceable.)

The Aircraft Armament Board Report

"Browning Caliber .30, for Aircraft Use

"(1) This Browning machine gun belongs to that class of automatic weapons known as short recoil operated, air cooled and belt fed. It is chambered for the standard caliber .30 U.S. ammunition. The force of recoil is utilized to perform the mechanical operations of feeding, loading, extracting, cocking and ejecting the empty cartridge cases through the bottom of the receiver while the buffer and driving spring returns the counter recoiling mechanism to battery position. The weight of this gun is 23.5#, being intermediate between the Marlin and the heavy Browning water-cooled machine guns. . . .

"(2) As the Browning aircraft caliber .30 machine gun now stands, the 2,576 plus 491 guns, as delivered by Westinghouse Company and the Marlin-Rockwell Corporation respectively, are faulty in their construction and have not been issued to the Service for general use. The Ordnance Department has undertaken the alteration of these guns and a remedy of all existing defects as well as adding certain parts necessary for convenience in mounting and ease of operation. This work is now in progress at Springfield Armory and has been reviewed by the Board which has witnessed the firing of some of these guns and has examined the drawings of the machine guns being tested. The Board recommends that all existing guns be modified to conform to the developed models and that enough squadrons be armed to give the gun as thorough an air test as is possible during times of peace. The remainder of the guns to be stored subject to Air Service requisition.

"(3) This gun is capable of firing standard .30 caliber ammunition at approximately 2,700 feet muzzle velocity and is effective against the ordinary targets incident to airplane combat. This gun, as modified, is capable of being mounted in such a way that its mechanism is readily available to the operator for the purpose of reducing jams and clearing stoppages. The gun itself does not develop during fire any particular stresses on the airplane to such an extent as to render its mounting difficult. One of the most commendable features of the gun is its high rate of fire, about 1,000 rds. per minute. It is thought this is the highest rate of fire that the gun can stand, on account of the character and weight of its construction, and it is not thought necessary to initiate any further development tending to give a higher rate of fire.

"(4) The gun is capable of being used with the Nelson Synchronizer and as modified renders its connection with this attachment a simple

Browning Aircraft Machine Gun, Model 1918, M1, Cal. .30.

matter. Its firing mechanism is of such character as to make it the equal of any synchronizable gun so far as its synchronizing properties proper are concerned. Its effective range is sufficient for present and future needs. Its cooling device is designed for use in aircraft and is satisfactory. The gun will withstand for a reasonable length of time storage on the plane itself and does not require the great care that other machine guns no on account of its large clearances and small number of working parts.

"(5) The gun can be disassembled and assembled in a comparatively short time and does not require an expert to keep it in proper working condition. The gun can be cleaned and repaired without removing it from its mounting and so not disturbing the sights. The gun is not sensitive to the action of dust and grit on account of the closed construction of its receiver.

"(6) It is regarded as possible to develop a right and left hand feed for the Browning aircraft machine gun for use with the existing gun. The Board recommends that this development be initiated and that when said development has been concluded it be given a thorough test, both on the ground and in the air.

"(7) The feeding device of the Browning aircraft gun is considered to be superior to all others.

"(8) The gun is capable of being fired from any position and will fire through an arc of 360 degrees except from a horizontal upside-down position, when the cartridges falling back in the receiver will probably cause jam.

"(9) The interchangeability of parts is sufficiently standard.

"(10) Although some of the major parts of the gun are interchangeable with corresponding parts of the Browning machine gun used in the ground service, the majority of parts are not interchangeable. Nearly all the differences in the two guns, however, have been dictated by a desire to obtain higher efficiency of the gun in the air and it is thought that no attempt should be made to accomplish an interchangeability between the ground and air Brownings. The Ordnance Department had initiated a project involving the manufacture of a new model

U.S. Aircraft Machine Gun, Model 1921, Cal. .30, Fixed.

Browning aircraft machine gun, which shall avoid all the faults in design made apparent in the first lot of Browning machine guns manufactured on drawings prepared during the war. The Board is of the opinion that this project is correct and recommends that it be carried to its completion, that a sufficient number of model guns be constructed to give a thorough service test and that all data relative to tools, gauges, fixtures and manufacturing drawings, methods involved, etc., should be completed and filed in the Office of the Chief of Ordnance and held available for future manufacture.

"The following changes have been found necessary in the Browning aircraft machine gun as at present manufactured and these changes are being incorporated in the re-development project now being followed out by Springfield Armory.

"(a) Adapters. These properly locate the mounting pins in respect to the feedway. The rear adapter includes also the stirrup for the support of the bottom plate and the forward one includes a bearing for the rocker shaft unit of the Nelson synchronizing gear.

"(b) Operating slide and handle. To permit greater accessibility, so far as loading arrangements are concerned, to the pilot.

"(c) New firing mechanism.

"(d) Modification of latch to include a positive lock. It is very necessary, as in the event of the gun flying open under the vibration of necessity encountered in airplanes, a failure to fire would result and consequent stoppage.

"(e) Addition to link guide to the front cartridge stop.

"(f) Removal of front.

"(g) Provision of means to hold the cover extractor spring in place.

"(h) Alteration of the angle of the breech lock cam and corresponding surface of the breech lock.

"From the original gun the following parts have been eliminated: (a) Mount adapters and rivets; (b) Elevating brackets and screws; (c) Cartridge stop, front and sear slide.

"The following parts are modified: (a) Barrel extension; (b) Bolt; (c) Cocking lever; (d) Cover; (e) Ejector; (f) Extractor cam; (g) Extractor cam plunger; (h) Latch; (i) Side plates; (j) Top plate; (k) Latch spring.

"The following new parts are added: (a) Bolt stud; (b) Cartridge stop, front, including link guide; (c) Included in (f); (d) Latch lock; (e) Operating slide and guides; (f) Firing mechanism; (g) Stirrup and rivets; (h) Trunnion adapters and rivets.

"Browning 11-mm Machine Gun for Aircraft Use

"A project has been initiated by the Ordnance Department . . . to develop a Browning 11-mm aircraft machine gun. The efficiency of this weapon depends entirely upon the efficiency of the ammunition. It would be a single purpose gun, probably used for the destruction of kite balloons. A short description of the 11-mm tracer incendiary ammunition, which would be the principal ammunition used with this gun, is as follows:

"The tracing incendiary composition consists of Barium Nitrate, Barium peroxide, powdered Magnesium and Carnuba Wax. The composition is contained in a round case bullet of brass hollowed out to receive it and is of such bulk that the bullet not only traces but has excellent incendiary properties. The muzzle velocity of the bullet is low, being about 2,000 feet per second, and the maximum trace is approximately 1,850 yards, varying from 1,300 to this figure. The

U.S. Aircraft Machine Gun, Model 1922, Cal. .30, Fixed.
This Weapon Was Designed to Feed from the Left or Right Side.

maximum powder pressures developed are low, lot exceeding 20,000# per square inch. The case is of brass and has a flanged edge for extraction. The facilities exist in the United States for the manufacture of this cartridge and there are on hand 1,182,580 rds. of 11-mm ammunition which will become useless in the event that the 11-mm machine guns (Vickers) are recalled from service. Considerable experiments have been continued on the 11-mm ammunition. By virtue of the bulk of the projectile, it has been possible to develop a highly efficient explosive bullet.

"Browning Caliber .50 Aircraft Machine Gun

"A project for the development of the Browning caliber .50 aircraft machine gun has been initiated by the Ordnance Department and a contract has been placed with Colt Patent Fire Arms Company, of Hartford, Connecticut. The specifications of this gun as at present defined, give the following characteristics:

"Weight--50 #.
"Rate of Fire--500-600.
"Muzzle Velocity--2,700 ft/sec. "Weight of Ammunition--1,830 grs. (about) (800 gr. bullet).
"Pounds per hundred rds.--26 (without links).
"Penetration--A. P. l 1/8" armor plate at 25 yds.

"This gun probably comes in a class of machine guns not peculiar to Air Service alone, and which are intermediate between the .30 caliber machine gun and small cannon. The tactical reasons for its development are as follows:

"(1) By virtue of the bulk of the projectile fired from this gun and the muzzle velocity with which it can be fired, it is anticipated that a much more efficient armor piercing, tracer and incendiary bullet can be effected. An explosive bullet can also be developed much more easily than in the case of a smaller bullet, like the 150 gr. .30 caliber now in use.

"(2) It is to be anticipated that a machine gun to be efficient against aircraft of the future must be efficient against light armor plate. Armored planes were coming into being at the close of the war, both on the part of the Allies and Germans. Against armor capable of being carried by aircraft our .30 caliber ammunition would be of doubtful utility and of necessity we must go to higher calibers and higher muzzle velocities to obtain an effective ammunition for such combat.

"This statement might be thought to be incompatible with some of the recommendations of the Board. It should, however, be borne in mind that aerial combat in the future may consist of several kinds of aircraft specially built to attain certain altitudes: that is,

"(a) High flying scout planes which may attain an altitude from 15,000 feet up and of necessity must carry light weapons and light ammunition to keep down the military load and to obtain a maximum effectiveness from the motor at altitudes at which they may be expected to fly.

"(b) Other low flying pursuit, aerial surveillance and artillery observation and day bombardment planes, medium pursuit planes, not intended to fly at such heights may be able to carry heavier weapons and a heavier weight of ammunition. These planes are the ones which may be expected to encounter armored airplanes, and consequently should be equipped with guns having the characteristics of the proposed .50 caliber Browning aircraft machine gun. It will be seen then that this weapon is not

U.S. Aircraft Machine Gun, Model 1922, Cal. .30, Flexible.
This Weapon Fired Over 20,000 Rounds in Test and Was Still Serviceable.

meant to replace the present existing .30 caliber weapons except in the case of planes working under 15,000 feet and so, as far as the general Air Service is concerned, should be classed as a special and additional weapon for which there will be a great deal of necessity. Work upon this gun has been undertaken by the Ordnance Department in connection with the development of a .50 caliber gun for ground and antiaircraft purposes. A priority has been established and approved by the Ordnance Committee as follows:

"(1) Aircraft .50 Caliber Browning Machine Gun.

"(2) Ground type .50 Caliber Browning Machine Gun.

"(3) .50 Caliber Tank Machine Gun.

"This priority is correct and it is thought that the aircraft gun should be given all possible preference.

"This development is not in such state now as to afford good grounds for any prophecy as to its ultimate efficiency. The Board has, however, examined all drawings available of the gun and of its ammunition and submits recommendations. . . ."

Browning Aircraft Machine Gun, Caliber .30

Before the Armament Board's report had even been put in rough form, work was well under way to correct one of the main faults with the original models. This bad feature was that the weapon fed only from the left, no provision being made to bring the cartridge belt from the opposite side. This made installation in planes quite a problem, especially where it was desired to place the weapons side by side.

Using one of the first guns completely modified according to specifications recommended by the Board, the project was begun at Springfield Armory. In a comparatively short time a prototype was finished to the point where its originators considered it ready for test. While the trial that soon followed showed numerous weaknesses, it did fire 10,000 rounds and, in order to avoid confusion, it was given the nomenclature, U.S. Aircraft Model 1921, Caliber .30.

Continued work was authorized not only to perfect the operating mechanism but also to incorporate a method of releasing the sear from the sides in order to synchronize by means of a solenoid. A second model embodying the desired features was ready in due time and 10,000 rounds were fired with only two breakages that required replacement. Half the ammunition was fed right hand and then the direction of feeding was reversed without incident.

This modified weapon was then sent first to Aberdeen Proving Ground, and following a successful trial, to McCook Field. After 20,000 rounds were expended, it was shipped again to Springfield where it was examined and found to be in good working condition. The experimental department recommended that with a few minor changes the model could be considered practically complete as far as specifications for this type of weapon were concerned. The only

Top: Browning Aircraft Machine Gun, M2, Cal. .30, Fixed.
Bottom: Browning Aircraft Machine Gun, M2, Cal. .30, Flexible (Sectionalized).

suggestion for further improvement was the addition of a rounds counter to inform the pilot of the amount of ammunition left in his feed boxes.

The weight of the gun was now 20 pounds and the rate of fire was officially set at 1,000 rounds a minute. In order to facilitate installation, numerous features were standardized so that it could be used fixed or flexible by changing the mounts. A method of placing twin guns on a Scarff ring was also worked out and specifications were written to take care of all future production.

During the period from 1927 to 1930 when Wright Field, Springfield Armory, and others continued to work on a light caliber .30 highspeed aircraft machine gun, no concise requirements had been prepared for inclusion in an official specification to cover military characteristics. These facts, as shown by the record, indicate considerable controversy as to what was wanted. When a real demand was shown in 1929 for such a gun to perform under the approved military demands, the Colt's Co. brought out the fully developed right- and left-hand feed gun that was later standardized as the Browning Machine Gun, Caliber .30, M2.

In developing this improved gun, every effort was made to retain the best features while simplifying manufacture. The type of steel that proved best was specified. Rivets were standardized, all being made with oval countersunk heads, wherever possible. Almost all basic dimensions were kept at an even fractional part of an inch and parts were designed for complete interchangeability in quantity production.

Everyone who worked on the project resulting in this M2 caliber .30 weapon deserves great credit for his contribution. By the late 20's it was a successfully tested weapon, capable of firing at the rate of 1,000 shots a minute. It could be fed from either right or left and seared off from the side by an electrically operated solenoid.

It is indeed fortunate that this work was done at the time, as practically all machine gun development stopped shortly afterwards, that is, as far as the United States was concerned. It was partly due to lack of funds but more from the peaceful lethargy that invariably settles on this country after each war. In 1938 the caliber .30 Browning gun, better known as the B. A. M. G., was still being made in very limited quantities with the same specifications as the original Model M2. As a larger caliber machine gun was still looked upon by the Air Force as a special objectives weapon, the caliber .30 was its first-line machine gun for both fixed and flexible mounting as late as 7 December 1941.

Browning Caliber .50 Aircraft Machine Gun

The Germans put a heavily armored plane into service during the closing days of World War I. This act made obsolete for all time the rifle-caliber machine gun for aerial use. Some countries were slower to accept the fact than others but nevertheless it cannot be disputed. The United States was among the first to come to this realization. The dramatic incident that caused it was the shooting down by such an aircraft of the young pilot, Quentin Roosevelt.

Gen. John J. Pershing, commander in chief of the American Expeditionary Forces, was among the first to see that the lightweight rifle caliber bullets would be ineffective against armored planes. With his characteristic promptness, he cabled the Army Ordnance Department to begin immediate development of a machine gun having a bore of at least a half inch with a minimum muzzle velocity of 2,700 feet per second.

At the time there was already under way an effort to use an 11-mm French cartridge in a Browning action, but when Pershing was informed that the velocity was not up to his requirements, he ordered renewed effort on the development of a larger cartridge and a higher bullet speed. The Browning caliber .50 machine gun that resulted was first made as a water-cooled weapon that later was lightened enough to be acceptable for aircraft use. The latter became known as the Browning aircraft machine gun, caliber .50, 1921. The water-cooled version also had the same model designation. In other words, for test purposes both a water-cooled and an aircraft caliber .50 gun were available and, while

First Trials of Browning Cal. .50 Machine Gun in Colt's Pasture.
Fred Moore Firing the Weapon and John M. Browning Standing.

operating parts were interchangeable to a limited degree, this did not hold true for most of the costly and vital components.

This condition existed until Dr. S. G. Green (colonel during World War II), who is now chief of the Engineering Section, Small Arms Branch, Industrial Division of the Office of the Chief of Ordnance, Department of the Army, conceived and put into effect the design of what is known now as the Browning Machine Gun, Caliber .50, Basic M2. This devisement allowed the manufacture of one receiver that could be used on seven different types of guns: Army and Navy antiaircraft water cooled, ground and turret-type heavy barrel, and fixed, flexible, and turret aircraft guns.

Dr. Green was awarded the Exceptional Civilian Award for his work prior to the war and the Legion of Merit for his outstanding commissioned service in World War II. There is no way to estimate the value of his contribution to the Allied cause, as it allowed wholesale production of a single type of receiver that could be adapted in a matter of minutes to any specific use required.

The caliber .50 machine gun initially developed by John M. Browning at Winchester and further refined by Browning and Fred T. Moore at the Colt's plant resulted in its standardization in two forms, the Browning aircraft machine gun, caliber .50, M1921, and the Browning machine gun, caliber .50, M1921, water-cooled. The guns were manufactured and used experimentally as aircraft and antiaircraft weapons between 1921 and 1937. They both had relatively lightweight barrels and the feed mechanisms were so arranged that the belts were fed from the left-hand side only. This meant that, when installed in pairs for either aircraft or antiaircraft use, the mounting was unduly complicated. The caliber .50 ammunition available during this same period had a velocity of

Aircraft Machine Gun, Model 1918, Cal. .50, Manufactured by Winchester Arms Company.

approximately 2,700 feet per second, identical with that of the caliber .30 ammunition.

The barrel of the water-cooled gun extended some 2 inches forward of the water jacket, which resulted in the muzzle becoming overheated when long bursts were attempted. The light barrels used on the aircraft caliber .50 machine guns also caused overheating after relatively short bursts. The weapon's limitations revealed in the early service trials of the water-cooled version raised a serious doubt with the Army and Navy during the period from 1927 to 1933 as to its potential worth either as an aviation gun or for antiaircraft use.

In the years from 1927 to 1930 the armed services made many studies on the employment of Browning weapons for all conceivable uses. Many comparative trials were conducted in aircraft with the Browning aircraft machine gun, caliber .30, M1921, and similar antiaircraft tests were made with the Browning machine gun, caliber .50, M1921, water-cooled. Limited experiments were also made with a heavy barrel type of the caliber .50 M1921 for arming combat vehicles.

No requirements were forthcoming prior to 1933 for an improved type of caliber .50 machine gun. The results of the past years were appraised and the problems given intensive study by Dr. Green between 1927 and 1932. The innovations disclosed were applied to a basic receiver and operating mechanism, which was so designed that seven principal types of caliber .50 Brownings could be readily assembled by the substitution of such parts as barrel jackets, barrels, and other items on aircraft, antiaircraft, combat vehicle, or ground-type machine guns. The elements replaced or added to the assembled weapons to adapt them to the specified use could be interchanged without the use of machine tools. No compromise, such as combinations, was made, and each complete assembly resulted in a superior gun for the required purpose.

The basic receiver had all the improved features, such as the right- and left-hand feed, and a new means was provided for obtaining a mechanical advantage in retracting the bolt. The strength of the driving spring and the weight of the barrel was increased to permit use of a more powerful cartridge, which allowed a longer barrel for maximum velocity and greater durability. The receiver and the fundamental operating mechanism were patterned after the caliber .50 heavy-barrel gun, developed earlier by Colt. It was indicated in 1932 that these advanced features developed by this firm, as represented by the pilot gun, and those developed by Dr. Green could be combined into a composite weapon that should and did give superior performance when used for the intended needs.

The Ordnance Department lacked funds in the period from 1927 to 1933 (as evidenced by the fact that not a single machine gun was manufactured in 1928) to undertake the development and production of a new type of caliber .50 gun for two basic reasons:

(a) The depression severely curtailed available funds.

(b) No requirement had been established for the development or manufacture of such a series of guns.

Consequently the limited funds available to the Army could not be spent for such a project. The Colt's Co., using components it developed on the heavy-barrel, air-cooled gun and the new

features developed by the Government, manufactured for the Ordnance Department in early 1933 two modified Browning machine guns, caliber .50 (later known as M1921A1); two Browning aircraft machine guns, caliber .50 (designated the M1921E2); and two improved Browning machine guns, caliber .50, heavy barrel. These were the first weapons to represent the combined innovations of the two models. They were tested at Aberdeen Proving Ground, Frankford Arsenal, Fort Monroe, and Wright Field, and were also demonstrated at the Naval Proving Ground, Dahlgren. Test results were most favorable and interest in the improved caliber .50 Browning was greatly intensified. When invited to furnish a complete set of ordnance drawings, the Colt's Co. suggested that their preparation at Springfield Armory from the firm's drawings, would be more economical.

During 1932 Gen. Samuel Hoff, Chief of Ordnance, Army, after observing concentrated activity on Dr. Green's part day after day, jokingly asked for an explanation. He replied that an attempt was being made to solve a problem having great bearing on the future of the caliber .50 machine gun, even though no requirement had been presented to the Ordnance Department. In order to do so, it might be necessary to apply the famous quotation by Thomas Carlyle framed on Dr. Green's desk--"He who would accomplish much must concentrate to such an extent that to the idle observer it borders on insanity." The general was also shown another saying, credited to Edison, which read: "I always do my best work when other people tend to their own business by going to sleep."

The Army, in 1933, without funds to carry forward the development of a complete series of new caliber .50 machine guns, interested the Navy in the results of the previous tests of both the aircraft and antiaircraft, water-cooled models. With the approval of General Hoff and Maj. Julian S. Hatcher (now major general, retired), Chief of Small Arms Division, Manufacturing Service, Ordnance Department, contact was made by Dr. Green with Commanders John J. Mahoney, Edgar R. McClung and Forrest P. Sherman (now admiral, Chief of Naval Operations), all of the Bureau of Ordnance, Navy Department, to determine whether they would be interested in the improved weapons. They responded enthusiastically and arranged for an early demonstration at the Naval Proving Ground, Dahlgren, Va. Commander Malcolm F. Schoeffel (now admiral) and Commander George F. Hussey, Jr. (later chief of the Bureau of Ordnance, Navy, now admiral, retired) were most interested in testing the new guns and aided

Top: Aircraft Machine Gun, Cal. .50, M2, Fixed.
Bottom: Aircraft Machine Gun, Cal. .50, M2, Fixed (Sectionalized).

materially in their early standardization for both the Army and Navy.

Further conferences were held with Commanders Sherman and Mahoney, who took the matter up with Admiral E. B. Larimer, Chief of the Bureau of Ordnance, Navy. The latter not only approved assistance in further research on aircraft and antiaircraft caliber .50 M2 machine guns but authorized an immediate expenditure in 1932-33 of approximately $150,000 to be used in the development and supply to the Navy of as many weapons as possible with the funds available. The Navy placed orders early in 1933 with the Ordnance Department of the Army for the manufacture by Colt of the basic M2 type improved caliber .50 machine guns. Navy funds were used for compiling data needed for drawings, manufacturing requirements, such as descriptions of procedures, technical notes, etc., later to be used in training manuals and maintenance work. These data were obtained by War Department personnel at the Colt's plant, where the many problems relating to production and manufacturing improvements were solved jointly by company and government representatives.

The support given by the Navy in the program was of material benefit in compiling instructional material, such as standard nomenclature lists, training manuals, specifications, and Government drawings during the development period at the Colt's Co. and at Springfield Armory. The funds made available by the Navy made it possible to set up a firm policy for preparing, first, basic drawings, and then establishing tolerances to govern both manufacture and final inspection. Colt's contribution with respect to the latter was outstanding, as evidenced by the very successful use of the Government drawings during World War II. More than eight major manufacturers produced interchangeable machine guns and components that gave outstanding performance, even though they were made in great quantity.

The development, pre-manufacturing study and production engineering during the initial manufacture of the caliber .50 M2 Browning machine gun were made possible by the unexcelled teamwork among Navy and Army Ordnance personnel, Springfield Armory, and the Colt's Co. The interest and support given by Admiral Larimer, Commanders Sherman, Schoeffel, Mahoney, and McClung, and by Navy financing made it possible to prepare a comprehensive and positive program to cover all phases of the problem. The work of Fred T. Moore, general works manager of the Colt's Co., and many of its production and design engineers, and by Maj. Guy H. Drewry (now general, retired), Mr. Hopkins, Mr. Ambrose, and other engineering personnel at Springfield Armory, was outstanding in the preparation and coordination of engineering data obtained for the most part from Colt's Co. and from Dr. Green, who worked at Springfield and at Colt's in directing the over-all program.

The restudies made during production engineering reviews included a consideration for the first time of building into an automatic weapon a measured reserve to insure reliable functioning under adverse conditions. A belt lift of 17 pounds was established as a minimum, it being appreciated that longer belts would be needed to obtain the full potential of this new type of gun. This was the first time that any automatic weapon had included in its specifications and drawings a definite measurable performance. This requirement was later increased to some 35 pounds by the Colt's Co. and the High Standard Manufacturing Co., working with Captain Adams of the British Service, when the increased throw of the belt feed slide was provided along with a wider cover.

The back plate was also replaced by one of much larger diameter, using Belleville washers of the type developed by the Colt's Co., the Fabrique Nationale, Mr. Hopkins of Springfield Armory, and Dr. Green.

Highly favorable reports were received from the battle areas of North Africa, Sicily, and on the continent of Europe on the caliber .50 guns, which showed that they were most reliable and their performance outstanding. A typical report is one received from the commanding general of the Army Air Forces (in November 1943) which states in part:

"1. The Commanding General of the Army Air Forces, with the full realization of the many outstanding achievements of the Ordnance Department in developing and producing large

Japanese Copy of the Browning Aircraft Machine Gun, Cal. .50, Type 1941, Fixed.

quantities of outstanding equipment for the United States Forces, wishes to specifically commend the Ordnance Department of the Army Service Forces for the magnificent achievement in furnishing the Army Air Forces with the most outstanding aircraft gun of World War II, namely the Caliber .50 Aircraft Machine Gun.

"2. This weapon, together with its ammunition, is the backbone of offensive and defensive guns for American aircraft and was brought to such a state of perfection by the Ordnance Department during the years of peace prior to the present conflict that it has enabled the Army Air Forces, the U.S. Navy, and Marine Corps to show a definite superiority in aircraft gun power throughout this global war."

Similar reports were received from the Army Air Forces Matériel Command during the last phase of the Tunisian campaign, where 72 enemy airplanes were destroyed with less than 200 rounds per gun expended on 35 fighter planes without a single machine-gun stoppage. M2 guns mounted on trucks also gave a good account of themselves and often supplied the sole means of protection of small supply convoys. A typical action shows that the drivers brought down two of five attacking enemy planes and scattered the remaining three.

The Navy and Marine Corps also had many reports of the Browning's excellent performance at Bougainville, Guadalcanal, and all other major operations. One such observation was the report of Capt. Malcolm F. Schoeffel (now admiral) to the Bureau of Ordnance, Navy, which showed that during a cruise of the Saratoga some 200,000 rounds of caliber .50 ammunition were fired with only two serious jams, and two dozen stoppages of all types. Captain Schoeffel declared that, although one of the purposes of his inspection trip in the Pacific was to locate troubles, he had difficulty finding them because of the high performance of the weapon.

A typical comment from the Armed Services Joint Report was:

"It is gratifying to note the acclaim with which the Caliber .50 Machine Gun is being received, for it is felt that this reflects, in a great measure, the efforts that have been expended in producing and accepting only quality weapons."

In World War II the M2 was produced by the following industrial firms: Colt's Patent Fire Arms Co., High Standard Co., Savage Arms

Corp., Buffalo Arms Corp., Frigidaire, AC Spark Plug, Brown-Lipe-Chappin, Saginaw Divisions of General Motors Corp., and Kelsey Hayes Wheel Co.

The translation of the new designs into a producible and dependable series of weapons by mass production methods showed that the groundwork and coordinated effort by the Army, Navy, and Industry team were well done and in a comprehensive form. Even though the production engineering data, drawings, and other information were in excellent shape, industry made a real contribution by applying new techniques with improved machinery, such as high speed broaching and multiple tools for performing rapidly many operations previously done separately.

Cycle of Operation

The following cycle of operation is for the Browning machine gun, caliber .50, basic M2, but with minor deviations to compensate for a difference in caliber, it will also cover the entire family of Browning short-recoil-operated machine guns.

When the trigger is pressed, the trigger bar pivots on its pin, causing the front end to press down on the tip of the sear. Its notch is disengaged from the shoulder of the cocked firing-pin extension, allowing it to fly forward and fire the chambered round. At this instant the barrel, barrel extension, and bolt, known as the recoiling portion, are in battery position.

The bolt is held securely in place by the breech lock, which extends up through the barrel extension into a notch in the underside of the bolt. After the powder charge explodes and the bullet starts to travel through the bore, the force of the explosion drives the operating parts rearward. During the first three-quarters of an inch of travel the breech lock is pushed off the breech lock cam step and out of the notch in the bolt by action of the breech lock depressors. This frees the bolt. As the recoiling portion continues to move back, the barrel extension rolls the accelerator rearward. The tip of the accelerator claws strikes the lower projection on the bolt And speed this part to the rear. The barrel and barrel extension have a total rearward travel of 1¹/8 inches at which time they are completely stopped by the oil-buffer body assembly.

During this movement the oil-buffer spring is compressed by the barrel-extension shank. The spring is locked in this retracted position by the claws of the accelerator which are moved against the shoulders of the barrel-extension shank. The action of the oil in the buffer tube aids the spring to cushion the shock of recoil of the barrel and barrel extension. During the rearward travel the piston head is forced back from the forward end of the oil-buffer tube. The oil at the rear of the tube under pressure of the piston head and valve escapes to the front. Its only path is through restricted notches between the edge of the piston-rod head and the oil-buffer tube.

The bolt travels rearward for a total of 7¹/8 inches. During this movement the nested driving springs are compressed. The rearward stroke of the bolt is finally stopped as it strikes the buffer plate and compresses the fiber discs to the

Loading Cal. .50 Ammunition on an F6F Aboard the USS Saratoga .

Browning Machine Gun, Cal. .50, Water Cooled, in Action as Antiaircraft Defense.

extent of one-eighth of an inch. Thus, part of the recoil energy of the bolt is stored in the driving springs and the remainder in the back plate buffer assembly.

After completion of the recoil stroke the bolt is forced forward by the energy stored in the driving spring and the compressed buffer discs. When the bolt has moved forward about 5 inches the top of the accelerator is struck by a projection on the bottom of the bolt. As the accelerator rolls forward from this blow, its claws are moved away from the shoulders of the barrel-extension shank to release the oil-buffer spring. The energy of the spring shoves the barrel extension and barrel ahead.

No restriction to motion is desired on the forward or counterrecoii stroke of the barrel and its extension; therefore, on the stroke additional openings for oil flow are provided in the piston rod head of the oil buffer assembly. The piston valve is forced away from the piston rod head .050 inch as the parts move forward, uncovering other openings. The resulting larger flow permits oil to escape freely through the ports in the piston valve as well as at the edge of the piston next to the tube wall.

As the barrel extension moves forward, the breech lock contacts the breech lock cam and is forced upward. The bolt, which has been continuing its forward motion after striking the accelerator, has now reached a position where the notch on its under side is directly above the breech lock, thus permitting the latter to engage its locking recess. The bolt is thereby locked to the breech end of the barrel extension three-quarters of an inch before the counterrecoiling parts reach their final forward position.

The act of cocking the gun is begun as the bolt starts to recoil immediately after firing. Thus the tip of the cocking lever, which is in the V slot in the top plate bracket, is forced forward. The lever is pivoted so that the lower end forces the firing-pin extension rearward. The firing-pin spring is thus compressed against the sear-stop

pin. The shoulder at the back end of the extension is hooked over the notch at the bottom of the sear under pressure of the sear spring. During the final forward motion of the bolt the tip of the cocking lever enters the V slot of the top late bracket. This action swings the bottom of the lever out of the path of the firing pin extension, allowing space for the pin to snap forward in fire the cartridge.

When the counterrecoiling portion is one-sixteenth of an inch from battery, the gun is ready to fire. If no trigger action is given at this instant, the operating parts assume final forward position and the gun ceases operation.

The belt-feed mechanism is actuated by the bolt. The ammunition belt is pulled into the gun by the pawl which is attached to the belt-feed slide. When the bolt is in battery, the belt-feed pawl has positioned a cartridge directly above the chamber. The belt-holding pawl is in a raised position behind the incoming round to prevent the ammunition belt from falling out of the gun.

As the bolt recoils, the belt-feed slide is moved out over the belt, and the belt-feed pawl pivots so as to ride over the next cartridge. At the end of the recoil stroke the throw of the belt-feed slide is sufficient to permit its pawl to snap down behind the incoming link in order to pull the belt into the gun. As the bolt moves forward on counterrecoil, the belt is pulled into the gun by the leverage exerted on the belt-feed pawl. The

"Eight-Gun Nose" Installation for B-25 Aircraft.
Each Browning Cal. .50 Is Provided with 400 Rounds of Ammunition for Ground Strafing.

belt-holding pawl is forced downward as a cartridge is pulled over it. When the forward stroke of the bolt is completed, the belt-holding pawl snaps up behind the next round and performs the function of retaining the belt in the gun.

As recoil starts, a cartridge is drawn from the ammunition belt by the extractor claw. At the same time the empty case is withdrawn from the chamber with its cannelure held in the T slot on the front face of the bolt. The empty case, having been expanded by the force of explosion, tends to stick to the walls of the chamber and the case may be torn if withdrawal is too rapid. To prevent this and to insure slow initial extraction, the top front edge of the breech lock and the front side of the notch in the bolt are beveled. Thus, as the breech lock is totally disengaged, the bolt first creeps away from the barrel and barrel extension in a gradual manner.

The cover-extractor cam now begins to force the extractor down, causing the round to enter the T slot in the bolt. As the extractor is moved, the lug on its side rides against the top of the switch, causing it to pivot downward at the rear. Near the end of the bolt's movement the extractor lug overrides the end of the switch, which then snaps back to its normal position.

On counterrecoil the extractor is forced farther down until halted by the extractor stop pin as the lug then rides forward under the switch. The incoming round in the T slot ejects the empty case. The extractor stop pin in the bolt serves as a means of positioning the incoming round, so that the cartridge, assisted by the ejector, enters the center of the chamber. When the cartridge is nearly seated, the extractor rides up its cam, compresses the cover extractor spring and its claw snaps over the cannelure of the cartridge in the feedway.

For automatic firing the trigger is pressed and held down. The sear is depressed as its tip is carried against the beveled surface of the trigger bar by the forward movement of the bolt near the end of the counterrecoil stroke. The notch in the bottom of the sear releases the firing pin, thus automatically firing the next cartridge at the completion of the forward stroke. The gun will operate automatically as long as trigger action is maintained and until the ammunition supply is exhausted.

The B.A.R. Since World War I

Following World War I, the exclusive rights to manufacture the B.A.R. (Browning Automatic Rifle) reverted to the Colt's Co. The Belgian Fabrique Nationale d'Armes de Guerre at Herstal, Belgium, was licensed in 1920 to manufacture and distribute the weapon in Europe, under the name Herstal light machine gun, along with many other Browning-designed guns.

In 1922 the United States Army brought out the Cavalry model 1922 machine rifle. This version of the B.A.R. had a heavy ribbed barrel, a bipod and an adjustable stock rest. A different rear sight from that of the model 1918 was utilized. The gun was never issued in great numbers.

Colt put the gun out in two commercial models. One was a military-type gun, equipped with a pistol grip and a light bipod fastened to the gas cylinder at its junction with the barrel. A number of foreign governments purchased this arm in considerable quantities. Another model of the B.A.R., called the Colt Monitor, was offered in 1933 as a police and bank-guard weapon. It was modified by a shortened barrel, the attachment of a Cutts compensator and addition of a vertical pistol grip. A number of these weapons appear to have fallen into the hands of criminals, judging from seizures made by the F.B.I.

Numerous foreign governments have employed the B.A.R. The Fabrique Nationale produced in 1921 a Swedish Army 6.5-mm model, having a vertical pistol grip and a slightly curved magazine. It is reported that a limited number in caliber 7.5-mm were manufactured by the Belgian plant for France or Switzerland or for the oriental trade.

After the 1914-18 war and up to 1936, the British tested the weapon and in 1922 provisionally designated it as the light machine gun to be produced in the event of another war. Later the Bren gun was standardized for the caliber .303 cartridge to fit this need. England's home guard was fitted with B.A.R.'s from the United States during the invasion peril of 1940 and 1941.

The Polish Army was supplied with the FN model 1928 B. A. R., firing the 7.92-mm

German Army type cartridge. And B.A.R.'s bearing the patent date 1932 were captured from the Japs in the 1942 Philippine campaign. These weapons had a 21-inch barrel of 7.7-mm caliber. The principal difference from American types was the hinged piston rod and forearm, permitting rapid removal of the gas cylinder.

The latest version of the B.A.R., which was supplied to United States armed forces in World War II, is the B.A.R. Model M1918A2. Weighing 19 pounds, it is heavier than the earlier models and is fitted with a flash hider and a medium-weight bipod at the muzzle. A conventional butt-stock without pistol grip is used. A decelerating device which can be thrown on and off allows a high and low cyclic rate of fire. There is no semiautomatic fire from this model, but the low rate of fire is such that single shots can be discharged easily by pulling and quickly releasing the trigger. There is no readily changeable barrel, so delivered fire is limited to what one barrel can stand in any brief period.

Models of Browning Recoil-Operated Machine Guns

The following tabulation lists the various models and bores of Browning recoil-operated machine guns that have been produced for use by the nations of the world:

Name	Country	Designation	Bore
Browning ground	U.S.A.	Model 1917	.30/06
Browning ground	U.S.A.	Model 1917A1	.30/06
Browning training	U.S.A.	Ml	.22
Browning tank	U.S.A.	M2	.30/06
Browning training	U.S.A.	M3	.22
Browning training	U.S.A.	M4	.22
Browning tank	U.S.A.	M1919	.30/06
Browning tank	U.S.A.	M1919A1	.30/06
Browning cavalry	U.S.A.	M1919A2	.30/06
Browning gen. purp.	U.S.A.	M1919A3	.30/06
Browning gen. purp.	U.S.A.	M1919A4 early	.30/06
Browning gen. purp.	U.S.A.	M1919A4 later	.30/06
Browning tank	U.S.A.	M1919A5	.30/06
Browning ground	U.S.A.	M1919A6	.30/06
Springfield ground	U.S.A.	Experimental	.30/06
Rock Island ground	U.S.A.	T13	.30/06
Colt ground	U.S.A.	Experimental	.30/06
Browning ground	U.S.A.	M1919 w/c	.30/06
Browning aircraft	U.S.A.	M1918	.30/06
Browning aircraft	U.S.A.	M1918	11 mm
Browning aircraft	U.S.A.	M1918M1	.30/06
Browning aircraft	II. S. A.	M1919	.30/06
Browning aircraft	II. S. A.	M1921	.30/06
Browning aircraft	II. S. A.	M1922	.30/06
Browning aircraft	U.S.A.	M2	.30/06
Browning infantry	Mexico	M1919	7 mm
Browning infantry	Argentina	M1928	7.9 mm
Browning infantry	Poland	M1930	7.9 mm
Browning	Bolivia	Commercial type	7.65 mm

Name	Country	Designation	Bore
Browning infantry	China	Commercial type	7.9 mm
Browning ground	Norway	M1929	7.9 mm
Browning ground	Norway	M1929T	7.9 mm special
Browning ground	Sweden	M1936	6.5 mm
Browning ground	Sweden	M1936	7.9 mm
Browning ground	Guatemala	M1924	7 mm
Browning ground	Guatemala	M1942	.30/06
Browning tank	Japan	Type 4	7.7 mm
Browning tank	Japan	Type 97	7.7 mm
Browning aircraft	Norway	M1929	7.9 mm
Browning aircraft	Greece	M1937	7.9 mm
Browning aircraft	France	Commercial type	7.5 mm
Browning aircraft	England	Mark II	7.7 mm
Browning aircraft	England	Mark II*	7.7 mm
Colt ground	Commercial	MG 38	Various
Colt ground	Commercial	MG 38B	Various
Colt aircraft	Commercial	MG 40	Various
Colt ground	Commercial	MG 52	.50
Colt ground	Commercial	MG 52A	.50
Colt ground	Commercial	MG 52-2	.50
Colt aircraft	Commercial	MG 53	.50
Colt aircraft	Commercial	MG 53A	.50
Colt aircraft	Commercial	MG 53-2	.50
Browning	Commercial	FN	.50
Browning	Commercial	FN	13.2 mm
Browning AA	U.S.A.	M1921	.50
Browning AA	U.S.A.	M1921A1	.50
Browning AA	U.S.A.	M2	.50
Browning AA	U.S.A.	M2 Navy special	.50
Browning aircraft	U.S.A.	M1921	.50
Browning aircraft	U.S.A.	M2	.50
Browning aircraft	U.S.A.	M2 Navy special	.50
Browning ground	U.S.A.	M2 HB	.50
Browning	U.S.A.	M2 HB Navy special	.50
Browning aircraft	U.S.A.	M2 TT	.50
Browning aircraft	U.S.A.	M3	.50
Browning ground	Guatemala	M1924	.50
Browning ground	Guatemala	M1942	.50
Browning aircraft	Japan	Model 1	.50

Chapter 7
Hotchkiss Aircraft Machine Gun

Aerial Uses of the Hotchkiss

The French were in many ways leaders in military aviation. One of their most creditable achievements was not being misled by the blind faith in dirigibles that was sweeping other countries. While the civilian population was terrified by them, military men always contended that the huge size of the airships would bring about their own destruction. In the matter of arming aircraft, while not the first to fire a machine gun from a plane, the French most certainly capitalized early on this accomplishment.

Two years before World War I a French Deperdussin monoplane had a machine gun permanently mounted on a post arrangement from which the observer located in front of the pilot could rise and fire over the propeller arc. As the gunner stood inside the rail, he was also partially protected by 4 millimeters of steel armor. This contrivance was originated by a M. Loiseau. Later the first public demonstration took place in February 1914 before high army officials at Villacoublay near Paris. The pilot for the occasion was Lieutenant Prevost, with M. Loiseau, the designer, acting as observer gunner.

The arrangement consisted of a machine gun attached in a yoke to a support braced to the mast and fuselage, with a high enough support to enable the gunner to fire forward over the propeller even with considerable depression. The operator was encased in a shield of light armor and had a light railing around the sides and rear. Even with these safety precautions he was still in danger, not only from falling out of the airplane, but from exposure to enemy fire.

The pilot's view was likewise obscured, even with small sections cut out of the trailing edges of the wings adjacent to the fuselage to allow him more visibility downward. Regardless of its clumsy appearance, it was at least an attempt to mount a machine gun permanently on a war plane. It was thought to be the only possible way to maneuver a weapon so as to fire forward of the propeller.

Even this method was not altogether original. There had been earlier experiments with a Nieuport plane where the observer merely stood up in his seat, braced his elbows on the upper wing and fired a repeating shot gun or military rifle forward in the same manner. However, in the Deperdussin plane the weapon was a mounted machine gun and the date, 11 February 1914, marked the first instance of a military plane with a permanently installed forward-firing machine gun. The weapon selected as the most suitable for aviation use was the light, or

Firing the Benét-Mercié Machine Gun from a Deperdussin Airplane, 1914.

"portative," Hotchkiss, better known in the United States as the Benét-Mercié.

Nothing was done to the weapon itself to make it more adaptable for aircraft use, but in other instances it was modified to feed by a belt in lieu of the strip feed. The time-honored system of having the belt and cartridges rolled on a drum and all attached to the weapon's receiver was used so as not to interfere with its flexibility.

An interesting sidelight in connection with this test is the relationship of the Deperdussin plane to the famous Spad machine, the finest Allied fighting aircraft in World War I. Armand Deperdussin was a French silk dealer who was reputedly very wealthy. He took to making fast airplanes as a hobby in 1911 and spent so much money on them that he went bankrupt. When his affairs were investigated, he was sent to jail for fraudulent transactions in silk.

Deperdussin was languishing in prison when one of his machines won the Gordon Bennett Cup in 1913 for flying at the record-breaking speed of 124.8 miles per hour. The pilot and others of the racing team sent a sentimental telegram of congratulations to their "bon patron" behind the bars.

Soon after the outbreak of the war M. Bleriot, another famous French pioneer of the air, took over the Deperdussin business to preserve the organization and staff of the firm. It then became known as the Société Pour les Appareils Deperdussin, from which the initials S. P. A. D. are derived. The plane was developed and perfected so that it became the one machine that assured the Allies air superiority in the war. It was fitted with an eight-cylinder Vee-type water-cooled Hispano-Suiza motor. This solid, fast and highly maneuverable plane carried twin synchronized machine guns and later was outfitted with one of the first air cannon.

Benét-Mercié Machine Gun Firing Forward.
The Propeller is Protected by a Deflection Plate Originated by R. Garros.

The science of military aviation was much farther along in France than it was with her English ally when war was declared by Germany in 1914. This was true not only with respect to the facilities at hand but likewise to pilots.

Of the earliest French fighter pilots one of the outstanding figures was Roland Garros, an airman of superb skill and daring. As early as 1912 he set an altitude record of 15,000 feet. During the war he had many exciting aerial fights ranging from the throwing of missiles to the use of the machine gun. It did not take him long after carrying the Hotchkiss Portative with him as a free gun to see the great possibilities of being able to fire straight ahead through the propeller arc. All pilots no doubt had noted the same thing before, but Garros was the type to do something about it immediately.

Early in 1915 he had his ordnance men mount directly in front of him a clip-fed Hotchkiss Portative machine gun. He had found out from confidential British reports on firing a machine gun forward through the air screw arc that with a normal rate of fire only 2 percent of the bullets struck the blade.

To the practical-minded Garros the solution of the 2-percent factor seemed simple. He fashioned two tempered pieces of triangular metal that could be clamped on the propeller so that when the blade was turned until the metal pieces faced the bore of the gun, it formed a pyramid. The sharp-pointed top of the triangular pieces then was bore-sighted with the center of the barrel. When a burst was fired, 98 percent went safely by the space between the blades and the other 2 percent ricocheted harmlessly off the hardened angles of the metal attachment, leaving the propeller unharmed.

Unfortunately for the Allies, Garros was forced down behind the German lines with motor trouble, although not before he had shot down many German planes with his device. His crude bullet deflector was shown to Antony Fokker, Germany's leading aircraft designer, who at once visualized an improvement and set about devising a reliable mechanical fire interrupter for his planes. The operation of the Garros deflector was one of the most sought-after secrets of the war, as the Germans could not fathom how he fired steadily through the air screw without injuring it. Garros later escaped to fight again, but by then his idea had been bettered and German planes began to appear with the fire interrupter that was to give them air supremacy for at least the next 6 months. Garros, nevertheless, was the first man to mount a machine gun in such a manner that maneuvering of the plane made it a gun-laying device instead of merely a flying platform.

The French, at the very outbreak of war, were ready with a secret weapon that made the world realize the effective use of the airplane against large movements of ground troops. Odd as it may seem, machine guns were not employed in the first ground strafing. The French high command had for several years prior to the war secretly practiced dropping bundles of steel arrows that separated on the downward flight. A bundle of a thousand arrows gave good coverage over a half acre of land. The missiles were very tiny and light, being 6 inches in length and brought to a needle point at one end. Tests made with them showed that, when dropped from 1.500 feet, one of them would go through the body of a horse. The Germans soon learned

An Early Front-Gun Spad with False Nose to Accommodate Gunner.

that dispersion on the approach of a plane was the best defense against the arrows and they soon were replaced by machine guns for ground strafing.

In order to regain air supremacy from the Fokkers with the fire interrupter, the French attempted to solve the problem of firing through the air screw of a tractor-type plane by equipping a Spad with a false nose in front of the propeller. It housed a gunner and a swivel-mounted Portative Hotchkiss. A wire guard kept the gunner's head out of the propeller in the event he thoughtlessly leaned back. This scheme only showed the desperation of the French at the time.

In 1916 the French developed another unusual fighting plane which was called the "Mechanical Owl." Its intended purposes were for night fighting, or more specifically, to seek out observation balloons, and for any other missions that required night flying. This plane was a pusher-type Maurice Farman, mounting a 11-mm belt-fed Hotchkiss in the forward part of the cockpit. It was felt that the large bullet held enough incendiary mixture to set fire to any observation balloon or hydrogen-filled dirigible. As further armament the large plane also carried six rockets, three on each wing, that could be fired electrically by the pilot. The rockets were considered extremely accurate up to 400 yards. The craft represented a formidable weapon against hydrogen-filled airships, both the fast-moving dirigible and the anchored observation balloon. Primarily designed for night fighting, the planes were equipped with a battery of headlights fastened above the landing gear and below the pilot. These searchlights served the dual purpose of lighting up the runway when the pilot returned at night to his home air base, and of illuminating the target once he could approach close enough to detect the huge balloon in the dark.

Benét-Mercié Machine Gun Adapted as an Aircraft Flexible Mount.

The rockets used on this plane were the invention of a French naval officer named Le Prieur and, while their use was restricted to observation balloons and Zeppelins, they had great potentialities in other fields. One of their most notable successes was the day before the great Somme offensive in 1916 when French pilots practically cleared the sky of the big hydrogen-filled bags, leaving the German artillery without observers.

The Le Prieur rocket was powered by ballistite. While the body was short and contained only a small amount of propellant, it was accurate for a reasonable distance after which it would wobble badly. This made it impossible to hit anything much beyond a 400-yard range. However, it was considered adequate for its intended use on the huge sides of a hydrogen-filled target.

Hotchkiss machine guns did not see much service in World War I as aircraft weapons. When the war came, France was desperately in need of heavy infantry-type machine guns and for this purpose the Hotchkiss was considered among the best. As fast as produced, they were sent to the front. The weapon, because of its design, could not readily be adapted to aircraft use, since feeding was done by inserting long metal trays of cartridges from right to left. This made plane installation practically out of the question.

Another reason for the sparing use of Hotchkiss guns was the fact that the British had two superb aircraft machine guns for free and synchronized installation. France, recognizing this, depended upon her ally to furnish armament for her planes. This is no reflection on the Hotchkiss. It was not originally designed for aircraft and some of its best features as an air-cooled infantry weapon made it impossible to convert to aerial use without practically complete redesign.

After the Armistice there was no immediate development work on machine guns at the Hotchkiss plant, but in 1922, at the suggestion of military authorities of other governments, the company did start experimental work on a large caliber automatic weapon designed primarily for aircraft use. Its operating mechanism was similar to the older models and a few features were added to compensate for the increased shock due to the high rate of fire demanded for such a weapon.

On the 13.2-mm aircraft Hotchkiss, cartridges were fed by means of a disintegrating metal belt that came in lengths of 100 to 150 cartridges. Although the quick-disconnect barrel was chambered for a cartridge with a tremendous powder charge, the design was so thorough that the great load was not excessive.

While produced at the suggestion of foreigners, as soon as this model made its appearance and showed promise in early firing tests at the Hotchkiss company's range, the French Government put its development in secret status. This act did much to retard progress on the arm and no doubt kept it from being used throughout the world by other powers.

The French air force visualized the 13.2-mm Hotchkiss as an ideal engine gun and mounted it experimentally to fire through the propeller hub of a Hispano-Suiza engine. When so installed in aircraft a compressed air cocking system was employed for both charging and solenoid operation. The rate of fire was 600 rounds a minute and the fast recoiling parts were buffed by a heavy spring-loaded plunger attached to the back plate. The bolt and piston assembly remained in the retracted position at the completion of a burst.

When thus mounted, the ammunition container was located above the receiver with a flexible cartridge guide extending over to the feedway. This ideal arrangement provided practically a gravity flow of ammunition into the gun once firing was started.

After the French had officially tested the gun at Calais until they were satisfied that they had an adequate machine gun for any aviation work that required a heavy high-velocity armor-piercing bullet, they then adapted it to be used on their own armored vehicles. A mounting arrangement was provided that gave the gunner a high degree of maneuverability. This particular Hotchkiss machine gun is little known because in the years between the two great wars the French, confident that it was their chief aviation machine gun for the future, suppressed all information concerning it. Before they could get

Hotchkiss Aircraft Machine Gun, 13.2 mm.

it into use on any large scale in World War II, however, the country was overrun by the Germans. The conquerors, already equipped with aircraft armament they felt superior, made no attempt to utilize the 13.2-mm Hotchkiss machine gun.

The basic principle being the same, the cycle of operation was naturally identical with that of other well-known Hotchkiss guns.

On 28 April 1927 representatives of the Okura manufacturing concern in Japan began negotiations with Hotchkiss for the purchase of manufacturing drawings for a large caliber antiaircraft machine gun. This gun was suitable for both shipboard and ground installations, having been developed from the aircraft 13.2-mm model. The French authorities permitted Hotchkiss to offer this same mechanism and caliber, withholding only information on the components that made it adaptable for aviation use. They specifically insisted that no means of belt feeding be revealed. The result was that the Japanese acquired the rights to make a 30-shot clip-fed weapon using the same operating parts as the original gun, but designed solely for antiaircraft use. It was a heavy-barrel weapon with radial fins for cooling that had a maximum rate of fire set at 450 rounds a minute. The Japs gave this devisement the official designation, 13.2-mm A. A. Machine Gun Model 93 (1933), and it was used extensively by them all through World War II.

In the Russo-Japanese War of 1904-05, which was the first major conflict in which both sides employed machine guns, the Japanese were armed with the Hotchkiss, which they found reliable and efficient. Since they were the victors and the Hotchkiss machine gun contributed to

Hotchkiss Ground Machine Gun, 13.2 mm.

the war's hasty conclusion, Japanese military men retained a highly favorable opinion of the weapon.

It was natural that Japan, in planning future offensives, placed the Hotchkiss high on the list to be adapted to its specific needs. Thus many Japanese machine guns were produced with strange appearances, designations, model numbers and physical outlines that actually housed Hotchkiss mechanisms.

These adaptations and straight copies ranged from lightweight infantry machine rifles to larger caliber antitank versions. Even standard ground Hotchkiss models, in a variety of calibers and provided with almost every conceivable feed system, were converted to aircraft use. Supply officers had seven distinct small arms cartridges to provide for troops that used such machine guns. In Japanese logistics it seemed to mean nothing if two machine guns were designated 6.5-mm; it was possible that the only identical thing about the caliber referred to was the bore dimension. In most cases each weapon had to have its own particular cartridge.

A fairly safe procedure of classifying a strange-looking Jap gas-operated machine gun was to look upon it as some form of Hotchkiss until proved otherwise. A few of the first-line Jap weapons that were undeniably Hotchkiss are given in the following table:

Model	Type	Year	Caliber
Light machine gun	11	1922	6.5   mm
Light machine gun	96	1936	6.5   mm
Heavy machine gun	3	1914	6.5   mm
Heavy machine gun	92	1932	7.7   mm
Antiaircraft machine gun	93	1933	13.2   mm
Tank machine gun	91	1931	6.5   mm
Aircraft machine gun	89	1929	7.7   mm
Aircraft machine gun	97	1937	7.7   mm
Aircraft machine gun	100	1940	7.92 mm
Aircraft machine gun	3	1943	6.5   mm

Tabulation of Hotchkiss Machine Guns

The following tabulation is intended as a ready reference of the various Hotchkiss models used by the nations of the world:

Name	Country	Designation	Bore
Hotchkiss	Experimental	Model 1895	8 mm Lebel
Hotchkiss	Chile	Model 1896	7 mm Mauser
Hotchkiss	France	Model 1897	8 mm Lebel
Hotchkiss	France	Model 1900	8 mm Lebel
Hotchkiss	France	Model 1914	8 mm Lebel
Hotchkiss	Mexico	Model 1896	7 mm Mauser
Hotchkiss	Venezuela	Model 1896	7 mm Mauser
Hotchkiss	Guatemala	Model 1896	7 mm Mauser
Hotchkiss	Spain	Model 1907	7 mm Mauser
Hotchkiss	Spain	Model 1914	7 mm Mauser
Hotchkiss	Brazil	Model 1896	7 mm Mauser
Hotchkiss	Ethieopia	Model 1914	8 mm Lebel
Hotchkiss	Belgium	Model 1906-1912	7.65 mm
Hotchkiss	Norway	Model 1898	6.5 mm Krag
Hotchkiss	Norway	Model 1898T	7.9 mm Jung TL
Hotchkiss	Sweden	Model 1900	6.5 mm Mauser
Hotchkiss	Commercial	Model 1899	As desired

Name	Country	Designation	Bore
Hotchkiss	Commercial	Model 1903	As desired
Hotchkiss (Navy)	Portugal	Model 1914	7 mm Mauser
Hotchkiss	Japan	Model 1905	6.5 mm Arisaka
Hotchkiss	Japan	Model 1914	6.5 mm Arisaka
Hotchkiss	Chile	Model 1920	7 mm Mauser
Hotchkiss	Japan	Model 1932	7.7 mm
Hotchkiss	Japan	Model 1941	7.7 mm
Hotchkiss	France	Balloon gun (World War I)	11 mm
Puteaux	France	Model 1905	8 mm Lebel
St. Etienne	France	Model 1907	8 mm Lebel
St. Etienne	France	Model 1907 T	8 mm Lebel
St. Etienne	Italy	Model 1907 F	8 mm Lebel
St. Etienne	Turkey	Model 1907 (converted)	7.9 mm Mauser
St. Etienne	Greece	Model 1907	8 mm Lebel
St. Etienne	Yugoslavia	Model 07/15	8 mm Lebel
Benét-Mercié guns:
Hotchkiss LMG	France	Model 09/13	8 mm
Hotchkiss Army	USA	Model 1909	.30/06
Hotchkiss Army	USA	Model 1910	.30/06
Hotchkiss Navy	USA	Mark I	.30/06
Hotchkiss Navy	USA	Mark I Mod 1	.30/06
Hotchkiss LMG	England	Mark I	.303
Hotchkiss LMG	England	Mark I*	.303
Hotchkiss LMG	Spain	Model 1922	7 mm
Hotchkiss LMG	Norway	Model 1911	6.5 mm

Chapter 8
Nambu Automatic Weapons

Between World Wars I and II, Japan constantly surveyed the development and experimental work of all nations in an attempt to provide for her own armament the best in automatic weapons these countries had to offer. The Japanese have long been noted for their lack of originality and their meticulous effort in copying, and later refining, those things in which they had special interest. Weapons were by no means an exception to this rule, since it was one of the first major powers to use machine guns in combat in the Russo-Japanese War of 1904-05. The automatic weapon used to such good advantage was the French Hotchkiss and the country naturally leaned towards this very reliable system of gas operation as a model for its future machine guns.

However, research was constantly directed towards the improvement of all makes of standard automatic weapons to meet specific needs of the armed forces. Manufacturing difficulties and metallurgy problems were often overcome by accepting a lower muzzle velocity, even the solution to muzzle flash being approached from this angle. Such sacrifice of bullet speed and the corresponding chamber pressures made it possible to get satisfactory operation from lower grade materials.

Since the trend was for the simplification of already existing weapons and the substitution of inferior metals, the development of aircraft machine guns and automatic cannon showed little or no originality, all being close copies of similar armament of other countries. One of their most popular aircraft cannon was a Browning aircraft machine gun seated up to 20 millimeters. Other arms were patterned after the German Rheinmetall and Italian designs.

One of the most discussed of Japanese automatic weapons was the so-called Nambu machine gun, devised by Lt. Gen. Kijiro Nambu. This officer first began the study of automatic weapons in 1898. In 1904, he designed a pistol, which, however, was not accepted by the Japanese Army. After modification, it finally became in 1925 an official side arm, being given the designation, Type 14 pistol. In the meantime he had turned his attention to machine guns. In his pistol he

Machine Gun, Model 3 (1914), 6.5 mm, Japanese.

did show some originality but his machine guns were straight Hotchkiss systems, with a few physical and external modifications to suit special conditions.

The first Nambu machine gun appeared in 1914 and was known as the Type 3 heavy machine gun. In 1922 it was improved and became the Type 11. General Nambu founded a rifle company bearing his name at Sankomaje-Nakano, Tokyo, in 1927. At this place he developed what was to become later the Type 92 medium machine gun which superseded the Type 3 in the Japanese Army. He again modified this medium gun as the need for its improvement had become obvious, producing the version known as Type 96.

In 1937 the Nambu Rifle Works merged with the Chuo Kogyo Kaisha Co. of Tokyo, and 2 years later he introduced the Type 99 light machine gun. Until his retirement in 1943 Nambu acted as an ordnance consultant to this firm. From 1939 to 1945 the Chuo Kogyo Kaisha plant manufactured 4,794 Type 96 and 1,179 Type 99 machine guns.

All Nambu machine guns were gas operated and air cooled with many radial fins giving more surface for cooling. The earlier models had rectangular gravity oil reservoirs so that as rounds were fed into the feed opening they engaged a spring-loaded lubricator. This action caused oil to flow through perforations onto the cartridge cases. Such lubrication was needed because manufacturing the components to such close tolerances as to permit a workable head space had not been possible at the time. The oil permitted the cartridges to slip back against the bolt until lock clearance was taken up, thereby eliminating the danger of a ruptured cartridge case.

The ejection system in these guns is the only deviation from the Hotchkiss, it being an exact duplication of the Lewis method of pivoting a piece over the bolt body. During forward movement of piston and bolt the bolt head raises the nose of the ejector upward out of the body, which forces the tail of the extractor to descend through the opening in the bolt. On rearward movement the aft end of the ejector lifts, causing the nose to descend through the opening in the bolt and strike the cartridge at its base. The case is then knocked through the opening in the side of the receiver. The rate of fire can be adjusted by means of five different sized orifices. The gas regulator has a positioning catch with a spring-loaded plunger that engages slots in front of the gas cylinder. Initial extraction takes place during the first phase of unlocking after the locking piece has risen and the bolt commences its first movement rearward. Full extraction occurs when the piece is unlocked and the gas piston and bolt assembly are driven back together. The extractor is the conventional flat-spring type with a recess cut in the back end of the barrel to ac-

Machine Gun, Model 01 (1941), 7.7 mm, Japanese.

accommodate it when the bolt is all the way in battery.

The Model 99 Nambu 7.7-mm light machine gun is undoubtedly the most familiar Japanese automatic weapon. The main refinement was in the machining which permitted better head spacing and consequently did away with the necessity of oiling the ammunition.

A new spring-loaded clip magazine was used that gave the gun the appearance of the well known Bren. Four different types of the Model 99 were tested before the weapon was fully standardized and adopted in May 1939.

To fire the Nambu Model 99 machine gun, the operator, generally prone, first snaps into its recess on top of the receiver a loaded clip. He cocks the gun by pulling back on the charging handle until the recess of the piston engages the bent of the sear, which holds the bolt back under driving spring compression. When the trigger is pulled, its nose depresses the sear, disengaging it from its recess in the piston. The bolt and piston now fly forward under energy of the compressed driving spring. During this movement the face of the bolt picks up the first round in the magazine mouth and starts it toward the chamber.

The bolt arrives home first and completely chambers the cartridge. With the extractor lip camming itself over the rim of the case, the piston, still moving forward, raises the back end of the bolt into its locking abutment by means of a linkage arrangement, and the projection on the end of the piston strikes the firing pin to explode the propellant.

As the bullet is driven out of the barrel, a portion of the gas is vented through the gas regulator into a cylinder to strike the piston head a sharp blow, driving it rearward. When the piston has traveled 3/8 inch, the bolt is free to unlock, forcing the aft end of the bolt out of engagement with the locking step.

The first recoiling movement begins initial extraction of the empty cartridge case and withdraws the firing pin. Continued movement brings ejection and full compression of the driving spring. A small spring-loaded buffer at the rear of the receiver absorbs all surplus energy and starts the operating parts back into counterrecoil. The cycle is repeated as long as the trigger remains depressed.

Chapter 9
Revelli Aircraft Machine Gun

The Italian Air Force during World War I was so desperate for an adequate rifle-caliber machine gun of native origin that it ordered the lightening of the water-cooled 1914 model Revelli. This was accomplished by the removal of the water jacket and use of an air-cooled barrel with longitudinal ribs. It not only gave more cooling surface but also strengthened the barrel, cutting down dispersion. The rate of fire was increased by use of ammunition more thoroughly lubricated by means of a built-in oil pump. While the modifications definitely improved the ground gun, it was still far from an ideal aircraft weapon. After limited use the Italians went back to the reliable synchronized Vickers for fixed installations and the Lewis gun for flexible mounting.

As soon as hostilities were ended, Italian military authorities immediately turned their energies towards the development of a light machine gun for both infantry and aircraft use. This trend was hastened by the British decision to stop exporting Vickers ammunition. They negotiated for the purchase of a thousand Darne guns from France but these proved unsatisfactory. The Italians wanted, if possible, for infantry use to combine the advantages of a light machine gun with the ruggedness of the heavy; and for the air force, to employ it both for flexible and fixed mounts.

They wished to raise the caliber to eight millimeters or even more, but were plagued by the presence on hand of huge stores of the outmoded 6.5-mm ammunition produced during the war. This obstacle forced them to do the next best thing, namely to improve what was already in use and if anything was designed in the future to be certain to chamber it for the readily available 6.5-mm cartridge.

Italy has always used the unique ordnance development method of giving contracts to different companies for machine guns based on identical specifications and then holding competitive trials to see which company has turned out the best gun. This odd system of government-sponsored competition makes identification very confusing, for one often finds practically identical guns, marked in some instances with the same model numbers, that are named for the various plants that produced them.

The Fiat Co., the first manufacturer of Revelli's guns, offered to the Italian Government for trial in 1926 a lightweight machine gun that it contended would fill all demands placed upon it. It was designed, according to its producers, to take into account reliability of action, minimum weight, simplicity of construction and ease of handling, all being factors that must be taken into consideration in order to have a practical unit. The principal parts were given as receiver,

Revelli (Fiat) Aircraft Machine Gun, Model 1914, 6.5 mm, Flexible.

barrel extension, bolt, breech lock, barrel, jacket, and ammunition box.

The receiver is square in shape. In its front there is an integral threading into which is screwed the cylindrical sleeve where the recoiling barrel slides. The operating or spade grip handle is fixed to the extreme rear of the receiver. The oil reservoir is located at the upper part of the receiver and is provided with a small hinged door for filling. On the right side of the piece an ejection slot is cut, while the left part has a portion milled out to admit the ammunition box.

The inside of the receiver has a longitudinal square cut in which the bolt and barrel extension slide during recoil. A rectangular transversal hole located in the middle accommodates the key that limits the sliding movement of the barrel and its extension. Another such slot near the handle serves for the key holding the spade grips into position.

The barrel extension is a square section with interrupted threads in the front part for quickly attaching the barrel. Its upper part has a rectangular opening through which the bolt lock is inserted. An opening on the left side admits the loaded round and on the right side there is a similar opening for ejecting the case. Internally the piece has a longitudinally square opening that serves as a slide way for the bolt.

The bolt is made square to fit into the barrel extension with a wider portion left on the aft end to engage the retracting hook at the bottom and the rear sear at the top. Internally it has a cylindrical hole of two different diameters into which the firing pin moves to perform its function. In the bolt face is a recess to accommodate the base of the cartridge. On the left side is a rib that engages the incoming round from the ammunition box and forces it into the chamber, while the extractor is fastened on the right of this piece. There is also a device housed in the bolt body called the safety fever. It prevents release of the firing pin before the breech lock is in battery position, since it cannot be removed from the path of the firing pin until its recess is reached which is coincidental with the locking action.

The bolt lock has a hole through which it is secured to the receiver by means of a pin, and around which it partially rotates during its function. The front flat part of this lock rests in the recess in the upper part of the bolt and the rear part on the barrel extension. On the upper part is a heavy spring-loaded curved rod to which is pinned the breech lock. The firing pin is cylindrical having two different diameters and is fitted with a rib which acts as a guide in the slot cut in the left side of the bolt. This rib has a cammed angle that causes it to be jacked back slightly by the first movement of recoil and at the end of the bolt's farthest travel rearward it is retracted fully. The weapon is fired automatically when the safety fever pivots down in the recess at the end of counterrecoil, releasing the cocked firing pin.

The barrel has externally cut longitudinal cooling ribs. It is attached to the barrel extension by insertion in the chambered section and is held fast by means of a four-tooth interrupted thread. A lever prevents the barrel from rotating and

Revelli (Fiat) Machine Gun, Model 1926, 6.5 mm.

consequently disconnecting itself from the barrel extension. This arrangement permits a quick barrel change and a short asbestos-lined handle is provided to facilitate this necessary action.

The weapon is hand charged by means of a handle that protrudes through the back plate with connecting slides that engage the rear end of the bolt at its rearmost projection. This permits hand cocking, as well as complete retraction of all recoiling parts.

The ammunition feed on the 1926 Revelli is a metal holder attached to the left side of the receiver. This device, which is normally removed during transportation, holds 20 rounds of ammunition and is held in place after insertion by a latch near its mouth. The ammunition is placed in the feed after first being inserted in a special metallic loading device. After this loading container is discarded, the last round to enter goes over a cartridge-holding pawl that retains it in position in the feed mouth. The rib on the bolt then picks it up for chambering.

The producers of the weapon recommended that the barrel should be changed after every 200-round burst and before firing suggested that the mechanism be worked back and forth manually a few times in order to lubricate thoroughly the ammunition before commencing to fire.

In order to fire the weapon, the following steps had to be undertaken to prepare it properly for reliable operation:

Check oil reservoir to ascertain if sufficient lubricant is in tank; pull rearward on the charging lug until rear sear engages bolt; push charging handle all the way home manually until it is locked by its detent; insert magazine in left side and lock in position; open trap door on right side to permit empty cases to be ejected; then introduce through this opened trap on the right side 20 cartridges from their metallic holder, pushing cartridges across the feedway until the last one crosses the holding pawl.

When the magazine was thus loaded, the container was discarded and the weapon was ready to fire.

The Fiat Co. appeared to have produced an entirely new machine gun but closer examination of the operating parts showed it to be just another version of the earlier 1914 Revelli with refinement being merely external. The basic operational features were the same as the original model. While the Italian Government did not adopt the "new" gun, it did encourage development by buying 2,000 for general use. This was enough financial incentive for the Fiat Co. to continue with its experimental work.

The manufacture of the 2,000 weapons that the Government agreed to buy was turned over to a newly formed corporation at Turin. Basically Fiat was an automobile manufacturing plant but since it found machine gun production a profitable sideline, a separate plant was built exclusively for the fabrication of automatic weapons. The new establishment was known as the Società Anonima Fabrica Armi Torino, which accounts for the 2,000 weapons, officially designated the Fiat, Model 1926, having a Safat name-plate.

It having been plainly pointed out to Fiat that all branches of the service were disappointed in the lack of new operational features in its 1926 model, the firm again proceeded with intentions of redesigning and manufacturing a suitable arm. As an incentive the Government withheld adoption of an official model, and development could be undertaken with the knowledge that appearance of a superior product could result in complete outfitting of all branches of the service with a suitable automatic firing mechanism.

The result of this second effort was the Fiat Model 1928. It had many features not to be found in previous designs. The caliber naturally remained at 6.5 millimeters and the rate of fire was the same, as was the feed system. This time the changes were internal and not external, as had been the case with the 1926 machine gun, the main modifications being in the locking components. The company, after many years of production, had finally dropped Revelli's retarded blow-back system and incorporated in this mechanism a positive locking arrangement invented by Giuseppe Mascarucci, an engineer in the employ of Safat. By this method the barrel and bolt were positively locked for the first fraction of an inch of recoil and at a predetermined distance the linkage pinned to the breech lock was raised, pulling the lock out of engagement with its recess in the bolt. This changed the action from retarded blow-back to straight recoil operation. The remainder of the recoiling parts, however,

Drawing of Fiat Model 1926, 6.5 mm.

Drawing of Fiat Model 1928, 6.5 mm.

were very similar in appearance to standard Revelli components.

The purchasing of the Mascarucci patents caused Revelli to terminate his business connections with Fiat after nearly 20 years' association. Although the company lost the services of one of Italy's most prolific automatic weapon inventors, there is no question that the Mascarucci lock was a worthwhile improvement and the army immediately ordered it into test status for the purpose of adoption. By early 1929 over 200 had been delivered to various proving grounds.

In the 1928 Fiat, the action was securely locked until the gas pressure had dropped to a safe operating limit, making lubricated ammunition unnecessary. The weapon, when correctly head-spaced, no longer had ruptured cases from the retarded blow-back type of operation whereby the lock seeks to become disengaged even while gas pressure is at its peak with bullet in the barrel. The minute opening between the bolt face and the breech end of the barrel resulted in separated cases when a point beyond the elastic limit of the brass was reached.

The weight of the gun without tripod or shoulder piece was 21 pounds. One of the most exorbitant claims ever made for a machine gun barrel was the producer's statement that with bursts of a length prescribed by proving ground regulations, the barrel could be depended upon to give accuracy for 20,000 rounds. The implication was made that some advanced heat-treat process was responsible for the phenomenal feat.

Disassembly without the aid of tools could be accomplished in a matter of seconds. Simplicity and the use of few moving parts were most certainly taken into consideration, as the bolt, firing pin, and two springs were all operating parts that could be withdrawn with the removal of the back plate buffer.

To fire the weapon, the operator is generally prone. After the box magazine is snapped into position on the left side, the bolt handle is grasped with the right hand and drawn to the rear. The rear searing device then catches in the notch in the aft end of the bolt, holding it in the cocked position. The firing pin is also retracted by this movement.

The special metal loading device holding 20 cartridges, inserted from the right hand side of the feedway and shoved in until the last cartridge is so loaded, passes over the cartridge-holding pawl. The metal charger is then withdrawn and put aside. The magazine now being loaded and the firing mechanism cocked, the weapon is ready to fire. If the pistol-grip trigger is used, it is pulled to the rear and with the aid of a bar raises the sear, allowing the action to be thrust forward by the energy of the compressed driving spring.

As the bolt goes home, the projection on its left side shoves the positioned cartridge in front of it into the chamber. The barrel and barrel extension are held to the rear, a half inch out of battery, by a small spring. When the locking notch in the bolt is directly under the locking lever, the whole assembly is then driven all the way into battery by the greater force of the driving spring. As the entire assembly moves forward, the link arrangement cams the lock into positive engagement with the recess in the bolt. This last forward travel of the bolt also brings into alignment the firing-pin recess controlled by the trigger bar. The open sear allows the firing pin to snap forward automatically and strike the primer of the cartridge.

While the peak pressure is in the chamber, the bolt latch securely holds the bolt, barrel extension, and barrel together until a half-inch travel is reached. The link now begins to raise the bolt latch slowly and then suddenly releases the recoiling parts with a small spring housed in the top of the receiver holding the barrel and extension in a retracted position. This gradual unlocking makes possible the slow pulling and loosening of the cartridge case by the extractor before total unlocking. The bolt is now free to travel rearward, assisted by considerable residual pressure in the bore acting on the face of the bolt. The extractor holds the base of the cartridge in position to strike the ejector and be thrown through the ejection slot in right side. At the first movement of recoil a cam surface action on the firing pin lug retracts it slightly beyond the bolt face. By the time two-thirds of the recoil stroke is accomplished, this piece is retracted. At the completion of recoil, the driving spring, being fully compressed, starts the bolt assembly forward to repeat the cycle of operation. However, if trigger pressure has been

released, the sear in the upper rear of the receiver snaps down and engages its mating notch in the bolt body holding the firing mechanism in a cocked position.

The Fiat Co. also made an attempt at this time to produce a 12.7-mm machine gun along similar lines, but did not get beyond a few working models that were tested by the Italian Navy for shipboard use against torpedo plane attack. It too was clip fed, a detail in itself that rules out its usefulness.

The next Fiat design was in the form of a larger caliber aircraft weapon. It was chambered for 7.7-mm rifle caliber ammunition with the use of a disintegrating metallic link belt in place of the box magazines that had by now become something of a permanent fixture with all Italian machine guns. While the operating principle was identical with the '28 model infantry gun, the rate of fire was later increased to 800 rounds a minute by the addition of a muzzle-booster recoil-actuated accelerator and a star-wheel recoil-actuated feed system. Otherwise all components were basically the same as those of the light machine gun.

The stepping up of the cyclic rate at first was not looked upon with favor by pilots and observers, who expressed themselves as preferring lower rates, with well regulated and reliable mechanism, to the faster firing. They argued that inaccuracy and waste of needed ammunition were the only results when a weapon was fired faster than it could be aimed properly. This viewpoint had much to do with the reluctance of the Air Ministry to specify anything beyond a normal operating speed for the armament of aircraft. However, when the 800-shot-a-minute gun did prove reliable to a certain degree, it did not take long for the flyers to reverse their former opinion.

Little was done in machine gun development in Italy until the mid-thirties when Fiat brought out another model at a time when the nation was faced with war.

No single action portrays so vividly the misguided helplessness of the Italians after a quarter century of effort to produce an adequate ma-chine gun of native design than did the appearance of the Fiat Model 1935. This gun was but

Fiat Machine Gun, 12.7 mm, Antiaircraft.

a rehash of the 1914 model Revelli, which was considered basically wrong from the start as an automatic weapon, since its locking system was operated by retarded blow-back. This meant that, from the instant of firing, the bolt, in trying to unlock, created a variable head space. Such a condition would result in ruptured cartridge cases unless lubrication were applied to allow them to slip in the chamber and follow the partially opened bolt rearward. Needless to say, the Fiat Model 1935 retained this feature. In fact many of them were actually modified weapons of the 1914 series, although some were of new manufacture.

The gun's chief modification consisted in the

Fiat Aircraft Machine Gun, Model 1928 A, 7.7 mm.

addition of a heavier barrel chambered for an 8-mm cartridge. Its chamber was fluted to aid in extraction of the case, since the splines in the chamber allowed gas to leak between the cartridge case and chamber walls. According to Revelli's patents, which he had assigned to Fiat before leaving the organization, the fluting would insulate the case from the chamber as adequately as oil. Such a theory must have been arrived at without test for rapidity of fire. There was no oil pump on the model, such as had been incorporated in the receiver of the earlier model. The change proved to be a mistake, as the fluted chamber functioned only at slower rates of fire when time was allowed for the high chamber pressure to drop before unlocking.

In order to keep the new weapon functional, there was added a device called the de-accelerator, that worked just as the name implied. It slowed the cyclic rate from a normal 500 to 120

Fiat (Revelli) Machine Gun, Model 1935, 8 mm.

rounds a minute. On the few guns that did not incorporate this feature the ammunition was lubricated by brushing on the oil externally before being loaded into belt or can. The feed box with its compartments could also be removed and an attachment substituted that allowed a non-disintegrating metal belt holding 300 rounds to be used if desired. Some guns were modified to feed from the left and eject to the right, and others made to do just the reverse.

A combined safety catch and charging lever on the rear cross-piece allowed both single-shot and automatic fire. A slotted or skeletonized barrel jacket with the front sight mounted on top was also added.

Another feature that will ever remain a mystery was incorporated. It was modified to fire from a closed bolt, an act that also showed adoption without ample proof firing. The latter would undoubtedly have revealed that any burst of great length through the air-cooled barrel, before letting the bolt go home on a live round, would result in a cook-off. The position of the combination bolt end and cocking piece was so located that if the gunner attempted to withdraw the live round from the hot chamber to prevent such a dangerous situation and the weapon did fire, as would be very likely under such conditions, the hand of the operator would be between the back of the bolt and the rear buffer.

The Fiat Model 1935 was perhaps the greatest known example of misapplied talent and inadequately tested theories in ordnance history.

Chapter 10
Bergmann, Dreyse, and MG-13 Machine Guns

German Light Machine Gun Models in World War I

The German high command early in World War I realized the need for a light companion arm for the heavy, water-cooled machine gun that lacked mobility for modern offensive infantry tactics. True, they had the ideal weapon in Heinemann's Parabellum but this weapon was in such demand by the air force that the thousands needed by the army were not available. The German ordnance department was also greatly concerned with producing the desired weapon as cheaply as possible with simplicity of design for easy mass production.

In early 1915 a conference was held and the best known German automatic arms designers were assigned the task of developing the proposed weapons. The Rheinische Metallwaren und Maschinenfabrik of Dusseldorf and the Bergmann Industrie Werke Abt. Waffenbau of Suhl were the companies selected for the undertaking. Rheinmetall was to produce the light highly portable machine gun for infantry use, while the latter plant would develop an aircraft version especially adaptable for flexible mounting. If this should prove reliable, it would free thousands of Parabellums urgently needed for fixed installations.

Rheinmetall, which owned Louis Schmeisser's patents upon which the action of the Dreyse machine gun was constructed, attempted to solve the problem simply by modifying the already existing Dreyse Model 1912. The parts were lightened together with a little redesign and a change in metal. The result, which used Schmeisser's pivoting lock, was given the factory designation, Dreyse Machine Gun, Model 1915. The change in manufacturing procedure and, in particular, the poor selection of metal resulted in a bad showing by the weapon during subsequent tests. It was practically dropped as a project until 1918 when more pains in manufacture and a better choice of steel resulted in a reliable gun that became known as the Model 1918. However the war was too close to its end to draw

Dreyse Machine Gun, Model 1915, 7.92 mm.

any conclusions beyond proving ground reports, which showed it to be an unusually good weapon.

The Bergmann Co. was more successful with its assignment. It likewise used the simplest approach by lightening the receiver and components of its well-known Bergmann action. Good engineering paid big dividends, as the improved design was successful from the start. But the failure of Rheinmetall to furnish an adequate gun forced the use of this weapon for infantry, because the critical need for this type of weapon gave it priority even over air force requirements.

When both companies were ordered to produce their respective models, it was understood that either could use any patented features belonging to the other. For this reason the guns have been frequently confused because of similarities in a few respects.

Bergmann Model 1915, N. A., Machine Gun

A prototype of the successful Bergmann World War I gun could appropriately be called the Model 1915. This weapon had a few features that were found by test to be unnecessary. It had larger holes in the barrel jacket, which was itself of greater dimensions. The so-called 1915 gun was rear seared and at the end of a burst a spring-loaded device caught and held the bolt in the cocked position. A pull on the trigger would release the firing mechanism to go into battery and fire the round.

The weapon that soon followed was given the designation, Bergmann Model 1915, N. A. (Neu Art, or new type). This weapon was equipped with a short shoulder stock and slotted barrel jacket for air cooling purposes. On the right side attached to the receiver was incorporated a curved sheet metal ammunition box holding 200 rounds of caliber 7.9-mm ammunition belted in either a web or a non-disintegrating flexible metal belt.

The weapon fired from the closed-bolt position, making a cook-off in an air-cooled barrel possible due to overheating of the chamber. Just why the rear searing of the prototype gun was not used cannot be readily understood, as it would have eliminated a very objectionable feature.

The main advantages found in the weapon were its simple but solid breech construction and the straight-line movements of all working components. The entire mechanism consisted of 81 pieces, and by raising the top cover all moving parts could be readily inspected or worked upon, if necessary. Although of rugged construction its weight still placed it in the light machine gun class. In the Model 1915 N. A., the use of a light barrel gave an increase in recoil speed over the one formerly used when it was water cooled. This hastened unlocking, thereby

Bergmann Machine Gun, Model 1915, N. A., 7.92 mm.

adding materially to speeding up the cycle of operation.

The action was operated by a system known as short recoil employing the typical Bergmann lock where a rising block, vertically positioned under the bolt, locked and unlocked by a cam. To increase the rate of fire further, an improved accelerator similar to that of the Dreyse was used. It consisted of a curved lever vertically pivoted to the receiver with its free end resting against the rear of the bolt. When the gun recoiled to the point of unlocking, the semi-circular portion of the accelerator was struck by the barrel extension's rearward traveling shoulder at the exact moment the depressed locking piece was disengaged from its recess in the bolt. This sudden blow and the mechanical advantage of the accelerator hastened the bolt rearward and gave a cyclic rate of 800 rounds a minute.

A redesigned and stronger rear buffer, housed in the short shoulder stock, was placed on this model to compensate for the increased speed. By checking the previous designs of Bergmann machine guns it appears that the German engineers took a few good features of other mechanisms and after further refinement added them to their own action.

The ammunition belt runs in a slot and its movement is governed by a ratchet slide block. The movement of the block is actuated by the recoil of the barrel. During the rearward travel the feed slide is carried to the right to be positioned behind the cartridge. During counterrecoil movement of the barrel, the slide block returns to place, causing the round to be moved over one space.

In order to facilitate movement and to avoid binding with the barrel caused by pulling the loaded belt over one space each time it feeds a round, the slide block is continuously forced to the left by a strong spring which is compressed by the barrel during its recoil movement. In the earliest of the Bergmann automatic firing mechanisms the locking of the breech is accomplished by means of a block capable of taking up motion in a vertical plane, this movement being regulated by guides in the receiver body. The block upon rising locks the bolt to the barrel extension.

The very earliest model Bergmann used a special push-out metal belt that permitted the cartridge to be shoved out of the link into the chamber. The Model 1915 N. A. employs either a metal or web belt that requires the pulling of the round out of its pocket to be carried rearwards slightly beyond its overall length before it could be positioned for firing. For this purpose a spring-loaded extractor claw in the feed slide removes the round and draws it to the rear. Another finger-shaped device, acting under influence of its spring, forces the cartridge down in front of the counter-recoiling bolt.

The Bergmann Model 1915 N. A. was of excellent design and had many features that made it highly adaptable for both aircraft and infantry use, but it was not so well known as other German machine guns. American ordnance officers in 1919, after the occupation of Germany, conducted a thorough test with the gun and reported it to be "well made, reliable and very light for a weapon of such rugged construction, but it did not show any outstanding features that were not already known nor was it considered as better than many other light machine guns of similar appearance." That the Germans counted heavily on the weapon is attested by the fact that after the Armistice the Inter-Allied Control Commission found over a thousand guns of this model in the Bergmann plant at Suhl.

To fire it, a loaded cartridge belt is placed in position and the tip is pulled to the left until the first round snaps behind the belt-holding pawl. The retracting handle is withdrawn all the way and released, only one pull being necessary to withdraw the cartridge from the belt and chamber it. The trigger is now pushed in to pivot the sear back, releasing the striker. Upon flying up, the latter hits the firing pin and detonates the powder charge. After the barrel extension, barrel and bolt recoil a distance of less than a half inch, the breech lock is cammed down by the angular surface in the bottom of the receiver. This forces down the front part located under the bolt, allowing it to recoil free of the heavier parts.

Actuated by the stud on the barrel extension, the accelerator then drives the bolt to the rear. The striker is caught by the bolt lock and held in its rearmost position by the safety sear. The base of the cartridge strikes against the right guide which serves as the ejector and kicks the

Components of the Bergmann Machine Gun, Model 1915, N. A.

empty cartridge out the left side of the gun at a downward angle. The claws on the main spring housing draw the new cartridge from the belt, and the housing, continuing to travel to the rear, contacts the feed lever by means of a stud. The longitudinal movement is thus translated into transverse motion, actuating the feed slide over one space, and positioning the incoming round.

The belt-holding pawl at the same time slips behind the next cartridge in the belt and holds it for the next phase. The claw on the main spring housing depresses the withdrawn cartridge into the feedway. The recoil stroke having reached an end, the stored energy in the driving spring then starts the firing mechanism forward. After chambering the round, the accelerator now releases the barrel and extension from a retracted position to go into battery. The locking block which is then raised by the cam on the bottom of the receiver locks the barrel, barrel extension, and bolt together.

The stud on the main spring housing carries the feed lever in all the way to place the incoming round against a cartridge stop in position for the extractor claw to slip over the cannelure of the cartridge. A projection on the barrel extension will trip the safety sear if the trigger is still depressed. And the last forward movement of the locked bolt and barrel releases the cocked striker that drives the firing pin forward to fire the next cartridge.

MG-13

After the Armistice the German ordnance department, when it found it was possible to

ignore the restrictions placed upon it by the Versailles treaty, attempted to develop an extremely light, short-recoil, air-cooled machine gun that could be transported and operated by the individual infantryman. Tactical changes had shown them that the lengthy bursts that only a water-cooled gun could perform were no longer necessary.

The Dreyse Model 1918 water-cooled machine gun, being one of the lightest and most advanced weapons of its type to date, was considered the most desirable to alter for this purpose, especially since a large number was on hand. There is a record that the Allied occupation commission found 3,000 finished weapons in water-cooled form in one factory as early as 1919. They showed great refinement over the earlier 1915 model. These much improved weapons had been given the designation Dreyse Model 1918 in the closing days of the war.

The guns did not see action against the enemy. They represented the best effort the Germans had made toward light machine guns and little was done to change them from their original form until Hitler came into power. Then all Dreyse machine guns in existence were immediately ordered to be reworked for the purpose of tightening and streamlining as much as possible. The firm of Simson & Co. of Suhl, Thuringia, was given the main contract to modify and refine the weapon.

It is very difficult to recognize the weapon

Machine Gun, Model 13, 7.92 mm.

visually as a modified Dreyse Model 1918. It is further confusing that under the Hitler regime all automatic weapons were given a number and no other form of identification. This particular weapon became known officially in Germany as the MG-13 and as late as 1935 it was the main machine gun for German infantry units and engineers and for anti-personnel use on tanks, armored cars, and motorcycles.

The principal changes on the MG-13 from the parent gun were the replacement of the water jacket with a ventilated air-cooled one, the addition of a lightweight shoulder stock and pistol-grip trigger housing, the elimination of the belt feed and the substitution of a spring-loaded slightly curved 25-shot magazine that could be filled directly out of the five-shot cartridge clips. When the last shot in the magazine had been fired, the firing mechanism was held back in the rear position by the slide catch. The cover group opened up as in the old Dreyse but the rear end or back plate was hinged down. These two operations made all working parts instantly available for inspection or maintenance by first swinging the accelerator out of the way. It also permitted dropping the hot barrel out the rear end in the event a quick change was needed. A selector switch located on the left side of the receiver over the trigger guard gave the gunner a choice of either single shot or automatic fire by mere pressure of the finger.

A combination muzzle booster and flash hider was used on this version. The booster, added to the recoil forces, gave a maximum rate of fire of 750 rounds a minute. A saddle-shaped drum magazine was later designed that held 75 cartridges and was mounted underneath the receiver. This design was resorted to in an effort to be able to carry enough ammunition in a magazine for a substantial burst and still not have the heavy loaded magazine too far off the center line of action. This would result in poor dispersion during automatic fire.

The gun's main importance lay in its use as a

German Troops Training with the MG-13.

training weapon for Hitler's new army while German manufacturers and inventors were working desperately to produce a more perfect instrument. The Dreyse MG-13's were eventually withdrawn from service and held in reserve until just before World War II. The bulk of them were then sold to Spain and Portugal. Spain retained the German designation but Portugal called them the Dreyse 1938 after the year of acquisition.

Chapter 11
Villar-Perosa Aircraft Machine Gun

On 8 April 1914 Bethel Abiel Revelli, then a major in the Italian Army and residing in Turin, applied tor patents on a machine gun designed primarily for aircraft use. This very interesting weapon was the forerunner of a number of aviation weapons invented by this officer. Revelli's claim to fame is originality of design, as is evidenced by his other machine guns the novel features of which have since been copied and adapted for present day weapons.

Revelli's attempt became internationally known as the Villar Perosa, because he assigned patent rights to a company of that name in Pinerola, Italy, which manufactured the unusual-looking gun. It was double barreled and could be fired simultaneously or separately at will. It may be classified as a retarded-blow-back, magazine-fed, air-cooled, dual-mounted aircraft machine gun. The short barrel version weighed only 14 pounds 4 ounces with the loaded 50-round magazine attached. The barrels were chambered for the 9-mm Parabellum pistol cartridge which was at the time being used in the Italian Army's service pistol.

The reciprocating parts, bolt and striker, were very light, weighing only ten ounces and had a travel of only 1 3/4 inches. This factor tended to give the weapon a phenomenally high rate of lire, it being officially rated at 3,000 rounds a minute, or 1,500 per barrel. Many guns were converted to ground use where they proved more successful than for aircraft. The small pistol-type cartridge did not have sufficient aerial striking power. Utilization of these weapons by infantry is said to have started the design of submachine guns for such a purpose.

A large number of Villar Perosas fell into the hands of the Germans and Austrians following the Italian disaster at Caparetto in October 1917. The Germans immediately set to work producing their version of a machine pistol that they felt was adequate to the needs of their infantry troops. It is odd indeed that the first weapon to be designed solely for aircraft failed in that department but showed a need for such a gun lot ground troops.

Major Revelli, in presenting his weapon before an ordnance board for an official test, described its action in the following manner:

"The Villar Perosa consists of two distinct but

Villar-Perosa Aircraft Machine Gun, 9 mm.

identical breech and firing mechanisms and is provided with barrels connected by a cross bar. It has two fixed handles one of which serves for training and the other for elevating purposes. Each of the breech and firing mechanisms comprises a hollow cylindrical casing provided with a lower lug and screwed to the corresponding rifle barrel.

In the breech casing a block provided with a projection carrying a handle slides longitudinally with a small rotary movement. The front and rear faces of the shoe or projection are each formed with a right-handed helical surface. It slides in a slot formed in the breech casing and is rectilinear for the major portion of its length, but helicoidal at its forward end wherein the projection is guided by two helical faces. The breech-lock is hollow and within it slides a cylindrical percussion pin or striker provided with a projection to guide it in the rectangular portion of the slot. The front face of the tooth is formed with a left-handed helical surface bearing on the helical face of the breechblock in order to insure the passage of the striker beyond the head of the block when the latter is rotated in its closed and locked position. The percussion pin or striker is hollow and contains in its interior a coiled spring that controls it. This spring is mounted on the guide rod of the closure plug screwed to the breech casing. Around the forward end of the breech casing a sleeve is rotatedly mounted provided with projections serving to fix the magazines during firing. A spring-controlled stop maintains the said sleeves in both positions. The breech is provided with a stationary or fixed ejector adapted to engage a corresponding slot formed in the breech-lock. The latter has a levered extractor pivoted and actuated by a spring.

The mechanism of each gun is naturally identical. Being in duplicate, they are connected at forward end by means of a bent cross member with the front sight at the forward end of the cross bar. The butt end carries the rear sight, which has a graduated opening for the different distances to be used in firing. This latter cross member is fastened at its forward end to two cylindrical cavities into which the two breech-locks are inserted, and held in place by means of pins. Below this piece two triggers are mounted, each having an L-shaped projection on the upper arm. This member also has a safety lever with spring stops governed by the controlling handle. Two lateral locking arms, according to the position of the handle, engage underneath the safety buttons and prevent firing or leaving the said buttons exposed to accidental contact."

Each magazine is provided with a socket having projections with which the sleeve engages as soon as it is rotated for fixing the magazine. The latter is somewhat curved in order to account for the slight conicity of the cartridges so that the latter, although superimposed in variable number, constantly present themselves in front of the barrel opening forming a certain angle with respect to the barrel. The magazine may contain 25 or 50 cartridges in double rows, whichever number is found necessary. It consists of a rectangular casing with rounded-off edges and terminated at the bottom with two lips that curve in such a manner as to retain the cartridges.

In order to fire the Villar Perosa, the breechblock is drawn backward by the retracting handle until it automatically engages its sear. Subsequently the safety lever is brought into the locked position. The cartridge magazine is then placed on the breech casing and secured thereto by means of the sleeve. The gun is trained, the safety is then rotated into a releasing position and the button depressed for firing. The breechblock and the striker advance simultaneously under the action of the driving spring and the former pushes a cartridge from the feeder into the chamber. At the end of its rectilinear travel the breechblock is forced to turn to the right under the action of the helical part of the slot formed in the breech casing. At the same time the striker continues to advance with respect to the block.

The sliding of the helical surface of the tooth on the corresponding face of the notch formed in the breechblock results in firing the shot. The gases of the explosive charge start the projectile through the bore while they tend to push back the breechblock. The latter offers resistance for a moment in view of the inertia of its mass and the resistance offered by the helical notch formed in the casing. Subsequently, it recoils completely withdrawing the empty cartridge with the

extractor until the cartridge strikes the ejector and is thereby expelled.

If the firing button is kept in a depressed position, the weapon fires continually until the cartridge magazine is exhausted. One of the most outstanding features of the Villar Perosa is the simultaneous closing of the breechblock with the advancement of the striker. The rear shoulder of the helical notch acts as a stop during the movement of parts into battery and as a friction brake to reduce the speed of unlocking during the first stage of recoil. The combined system has only a single degree of freedom, so that any displacement of either one of these two elements (the breechblock and the firing pin) definitely constrains the movement of the other.

Chapter 12
S.I.A. Aircraft Machine Gun

One of the early Italian designs of an automatic firearm was originated by Giovanni Agnelli, of Turin. Although he applied for a patent on 17 February 1914, the weapon lay dormant for several years. Agnelli's rights were assigned to the motor firm, Società Italiana Ansaldo of Turin, and hence acquired the designation, S.I.A. Near the close of the conflict the government of Italy placed an initial order with the Fiat Co. of Turin for 10,000 aircraft machine guns utilizing Agnelli's S.I.A. design. Each gun, complete with necessary spare parts and 15 magazines, was to cost $320 at the factory.

The weapon was chambered for the 6.5-mm model 1891 infantry rifle cartridge. This specification in ammunition was considered very important in Italy since its other machine guns were chambered for several different calibers making the burden of supply heavier. Great Britain had heretofore furnished ammunition for Italy's automatic weapons and it was felt that should England not be able in the future to export this crucial item the situation would be desperate. It was therefore decided to standardize, beginning with this machine gun, all future design in order that the Italian infantry rifle cartridge could be used.

In early tests the S.I.A. aircraft model gave what the authorities termed "satisfactory results," both as a free gun and fixed installation. When used as a free gun, it was invariably mounted in pairs. It did not, however, give good enough performance to take the place of the English Vickers then being used in the fixed forward firing positions. Still, the S. I. A. was modified to take the Vickers synchronizer in the event a change-over should prove necessary.

Neither the S.I.A. aircraft gun nor its ground model saw service in World War I. Although 2,000 were manufactured for the air force and 3,000 for the ground forces in the summer of 1918, the actual date of issue was immediately after the Armistice. It is believed that the Italians were holding them until perfected so they could be thrown into the big spring offensive planned for 1919. Immediately following the end of hostilities the army, confident of its superior design, issued the S.I.A. as its standard light machine gun and it was so considered throughout the twenties. It had a maximum rate of fire of 700 rounds per minute.

The vertical-type magazine held 50 cartridges for ground guns and 100 for aircraft use. Its body was rectangular in shape and made of stamped sheet steel, the cartridges fitting into place in an oblique angle five cartridges in width. This unusually wide magazine located in the center of the receiver made the weapon unwieldy, es-

S.I.A. Aircraft Machine Gun, 6.5 mm.

pecially with the 100-shot version, while sighting had to be mounted in a well offset position to compensate for the magazine.

Both the aircraft and ground guns had spade grips and all other features were identical, except for the cooling system. The aircraft model had long splines cut the full length of the barrel. This advanced feature not only gave greater radiation surface but also strengthened the barrel greatly, cutting down dispersion. The ground gun employed a heavy barrel together with unusually large circular aluminum fins, that extended all the way to the flash hider. For some unknown reason these fins remained the same size the entire length of the barrel, giving the weapon an extremely heavy appearance. On another style of barrel assembly the radial fins increased in size as they went forward, creating the most awkward silhouette to be found on any machine gun.

A collar-shaped device located on front of the trunnion joined the barrel and trunnion by a quarter turn rotation. The funnel-shaped breech end of the barrel served as a cartridge guide. The sight arrangement, which was offset to the left of the magazine, consisted of a rotating three-part affair graduated at 300, 700, and 1,000 meters. The charging handle was located on the right side and after full retraction it was shoved forward by the gunner until it locked in its spring-loaded detent.

The safety, located on the upper right rear on the receiver, was marked S (for Safe) and F (for Fire). The S.I.A. had no provision for single shots and when the gunner pushed selector button F, full automatic fire was accomplished. The

S.I.A. Machine Gun, 6.5 mm.

S.I.A. Aircraft Machine Gun, 6.5 mm, Dual Flexible Mount.

ejector, which was fastened in a T slot in the receiver body, passed through a slot in the bolt body. A recess was cut in the rear of the bolt to furnish a relief at the point where it turned to lock.

The sides of the ejection slot in the bottom of the receiver were machined to permit the addition of a container to catch the empty cartridges. This arrangement was used when the gun was mounted as a free gun to prevent flying brass from injuring tail surfaces of the aircraft or hitting other friendly planes in formation.

The bolt was round on its rear portion with its front half cut away to form a flat surface a little above the center line of the firing pin. On the right side appeared the locking lug, a beveled projection that traveled in a slideway until it was cammed down in the receiver body's locking recess by the advancement of the firing pin lug housed centrally in the bolt body.

To fire the S.I.A., the operator installs a loaded clip in its recess on the receiver until the release lever on the front of the bracket clicks, shoving it securely in position. Then as the charging handle on the right is grasped, it is freed of its detent-holding pawl and pulled rearward. The front bottom piece of the retracting assembly has a cam angle cut at this point that engages the locking lug and frees it from the receiver to which it has been locked. This movement also jacks the firing-pin assembly back to the cocked position by partial rotation of the engaging cams. With the weapon unlocked and firing pin retracted, the recoiling assembly is pulled rearward until the searing device in the upper part of the receiver drops into its recess. All parts are held to the rear under tension of the driving spring that has been compressed by the retracting movement.

The charging handle is then shoved all the way forward until it is locked in place by a short spring-loaded detent. Such locking is very necessary before firing in order to prevent faint strikes.

If the selector has been set on F and the trigger button pushed forward, the entire firing mechanism is impelled forward by the large driving spring. As the upper bolt face passes the rear of the magazine, it strips the positioned round and starts to chamber it. Continued forward travel carries the nose of the bullet into the funnel-shaped recess in the barrel's breech that guides the ammunition into the chamber.

When the lug on the bolt has reached a place above the locking recess in the receiver, the round has been fully chambered. The 45° angle

Section Drawing of S.I.A. Aircraft Machine Gun.

on the firing pin, riding in engagement with the corresponding angle in the bolt body, rotates the bolt a fraction of a turn downward, freeing the firing pin to continue advancement under influence of the operating spring. This drives the firing pin into the primer to discharge the weapon.

Until the bullet is out of the bore, the gun is secured by the locking lug of the bolt. Its disengagement with the face of the locking recess in the receiver is thus slowed. This slight hesitation is known as retarded blow-back, as the locking angles hold only long enough to permit the bullet to clear the muzzle. The weapon then unlocks and the blow-back, or high residual pressure in the bore, further actuates the mechanism.

The bolt starts rearward, carrying with it the lubricated cartridge case, held by the extractor at its base until it collides with the ejector that is riding in a groove in the bolt body. When struck, the base of the round is pivoted down out of the ejection slot in the bottom of the receiver. The strong driving spring, the only spring working during operation of the weapon, is being compressed all the time until it stops the bolt before it reaches the rear of the receiver. If the trigger button remains pushed in, the cycle of operation will repeat itself.

Chapter 13
Gast Aircraft Machine Gun

After the successful conclusion of World War I as far as the Allies were concerned, it was found the Germans had been desperately trying to put into action a secret weapon, namely a machine gun capable of firing at a rate of 1,600 shots a minute. In order to turn out this high-speed gun, it was given the highest priority of manufacture, even over aircraft. The weapon first produced in January 1916 by Carl Gast of Barmen, Germany, was very similar in principle to an automatic machine gun patented by Bethel Burton in Great Britain 22 March 1886 (No. 4,008). It was a double-barrel machine gun of the recoiling type. The object was to provide an improved means of operating the firing mechanism and in doing so, to produce a cyclic rate higher than is found in standard automatic weapons.

In order to accomplish this, the two barrels were combined in such a manner that each recoiling breech and firing mechanism furnished the energy to lock and fire the other. The whole system was based on the fundamental idea that with the explosion of each shot, the recoiling force from one barrel could load, fire, extract, and eject the rounds in the other barrel. In this way a series of uninterrupted shots could be obtained. In trials the Gast fired at rates of 1,600 rounds per minute, as issued, and with a spring-loaded recoil adapter to buff the action and hasten its return, cyclic operation was stepped up to a rate of 1,800 shots per minute. There was also a means of firing single shots if desired, and the construction was such that should one barrel be put out of commission, the other barrel could fire single shots.

The ammunition was not fed in belts of disintegrating links, as was customary, but in magazine drums that were fastened by slipping them into position on the sides until the holding latch snapped into place. These flat circular drum feeds were placed on the sides in order to make ejection possible from the dual mounting. Each drum, which contained a strong spring that was compressed tighter as each cartridge was placed in position, had a maximum capacity of 180 rounds of the standard German 7.9-mm rifle caliber machine gun cartridges. The changing of the feed devices was accomplished by an experienced gunner in a matter of seconds. The light weight (60 pounds without ammunition) and the

Gast Aircraft Machine Gun, 7.92 mm.

phenomenally high rate of fire made the German air force feel that the Gast was the perfectly designed aircraft gun and according to all available records it was expected to sweep the skies clear of opposition if enough could be installed in time.

For aircraft installations a high-power telescope with cross hairs for sighting was mounted on the receiver midway between the magazines. Another attractive feature was that all working parts were instantly accessible by the application of thumb pressure on the back plate latch. One minute was all the time required to field strip the piece.

Following a successful demonstration of the Gast, promoted by Vorwerk and Co. of Barmen on 22 August 1917, ordnance representatives were so impressed that the company was immediately given an order for 3,000 guns with necessary spare parts and ten drums for each gun. They were likewise given the highest production priority. A price of 6,800 marks per unit was set, including the drums.

Vorwerk agreed to the terms and promised to furnish 100 complete units by 1 June 1918 and to increase delivery by 100 a month until September; after that it was estimated 500 a month could be delivered. Records show the contracting company delivered far more than promised. Such results can be accounted for by every effort being made to supply vitally needed materials to the firm for production, sometimes at the expense of other badly needed equipment. This fact shows that the authorities looked upon the Gast as the one thing that could change the desperate situation of the Germans when they lost air supremacy to the Allies.

The following letter from the commander of the German Trial Section for Arms dated 20 September 1918 to Vorwerk indicates the desperate pressure being put on the company:

"Referring to my repeated telephone conversations of these last days with your firm, I request you once more to deliver Gast machine guns with the greatest possible speed.

"The strained situation on the battle fields urgently requires the use of superior and most modern arms. The Gast gun is being used with great success on battle-planes, for scouting as well as for antiaircraft. I therefore urge the firm to deliver these guns in large quantities and with the greatest possible speed.

"Changes in construction are not necessary on account of the present favorable results and the reliable working of the guns. A further order of about 6,000 guns will be passed shortly by the office involved.

"With a view to the favorable reports which reached the commanding general about the Gast gun and his request for more machine guns, I feel obliged to point out to you the necessity of the prompt delivery of large quantities.

"(Signed) Lochte,
"Commander of the Trial Section for Arms."

While records show they had limited use in actual warfare, the secret was kept so well by the Germans that not until 3 years after the Armistice did agents of the Inter-Allied Control Commission uncover a secret hiding place near Königsberg, where 25 Gast machine guns, ammunition, and manufacturing drawings were found. They were turned over to the

Gast Aircraft Machine Gun, 7.92 mm, With Feed Drums Removed.

Aeronautical Control Commission in Paris for study and test.

Army Intelligence a short time later gained possession of a letter from the German office of aeronautics, an agency that according to the Versailles Treaty was not supposed to be in existence. This agency, operating secretly, as can be readily seen from the contents of the translated captured documents, was not only functioning but was also trying to arm Germany with the last word in aircraft machine guns for the day she would again take the field against the world. This letter to Vorwerk & Co. from the underground German bureau is given verbatim, as it shows better than any other medium of expression not only its high regard for the Gast gun but also its careful preparing for another war:

"Charlottenburg, Nov. 18, 1921.

"The firm Vorwerk & Co.,
         Barmen.

"The Gast gun made by you having become of no use any more at the front, I feel obliged to state that at the present moment we still consider the gun of the latest type. The accuracy of the work and the firing were never, not even approximately, attained by the other hitherto existing machine gun systems.

"We may say that the Gast gun may be qualified as the ideal of the aeroplane armament. We also declare that you can further continue delivering the remainder of the complete order for 3,000 guns.

"If, with a view to the present circumstances some doubt might have arisen as to this delivery, I certify herewith that we shall fulfil the obligations of the contract. I enclose herewith certificates from the command of the trial section at Döberitz as also from the officer in charge of the Air Service who gave his instructions for the use of the weapon in flying planes at the front.

"Thanking you for having provided the Aviation troops with such a remarkable gun, I shall also be very much obliged to you if you will also thank the constructor, the engineers and work-men who handled this arm.

"(Signed) Bufe."

After the uncovering of the Gast guns and manufacturing drawings the American Ordnance Department requested that the Allied Commission make available for test and evaluation at least one of the guns and 4,000 rounds of ammunition. After exchange of much correspondence, on 14 March 1922 one Gast gun, serial number 156, and 3,838 rounds of 7.9-mm rifle caliber ammunition were received by the property officer of the Munitions Building in Washington, D. C. However someone negligently forgot to send the drum magazines and there was another long delay before the weapon could be officially tested at Springfield Armory, Springfield, Mass.

In the meantime the War Department was notified that United States patent rights had been assigned by the inventor to a mechanical engineer, Mr. H. C. Isenberg, of the George W. Goethals Co., New York City, and that, if the Army was interested in the gun for purposes of adoption, Isenberg would represent Carl Gast. After limited firing on the Springfield range the following conclusions were reached by the examining board which met on 17 August 1923:

"The Ordnance Department having tested the 7.9-mm machine gun is now familiar with its construction, operation and functioning. . . . The gun is practical mechanically and operates reliably. It is sturdy and a good type of recoil operated machine gun. However, it offers no advantage over standard types now in use in the United States Army, and if adopted would require entire new facilities for its production. As it is not believed to be superior to the Browning gun, and as there are ample manufacturing facilities for the Browning gun, the recommendation is made that no action be taken looking into the acquirement of any rights in manufacturing the Gast gun or acquirement of additional ones for further test."

The report was signed by J. P. Wilhelm, Assistant to the Adjutant General, U.S. Army.

The American representative, Mr. Isenberg, feeling that the weapon had not been subjected to enough test to warrant rejection on the grounds stated above sought through the Secretary of War to have the board submit to him a written statement as to the reason for rejection on evidence gathered from actual test. He insinuated that it was not proper to come to a

Breech Mechanism of Gast Aircraft Machine Gun.

conclusion that a weapon had no value to the Army when it did everything claimed on submission for testing. The Secretary of War refused this request and nothing more was done about the Gast in the United States.

To fire the Gast machine gun, the operator first places into position two loaded drums and pulls the loading lever with the right hand smartly to the rear until the firing mechanism, then in its most retracted position, goes fully into battery. On the way forward the bolt face forces the incoming round into the chamber and the firing pin is compressed by means of a stationary collar contacting the U-shaped projection to which it is attached.

During the last portion of forward travel the release pin of the charging lever strikes against the slide stop and swings it out in such a manner as to disengage the charging lever, so that it will remain stationary during firing. This slight motion of the stop slide causes the locking discs to strike their camming angles, thereby rotating them until the rear face of the discs is arrested and the bolt and barrel are securely locked to the extension. While the firing mechanism is in battery and ready for firing, the bolt

Gast Aircraft Machine Gun, 7.92 mm. Top View with Feed Drums in Place.

assembly of the opposite barrel is at the extreme distance rearward it can travel.

A single trigger operates both mechanisms through a trigger bar contacting each sear, which, upon being pulled to the rear, allows the spring-loaded firing pin to fly forward and fire the chambered round. The barrel, bolt, and breech slide (barrel extension) recoil together for a short distance, at which point unlocking begins. Complete unlocking of the breech lock from the breech slide is caused by the face of the locking discs striking the fixed cam. The timing is such that the tip of a lug will strike the breech-lock lever at the moment of unlocking. The impact of the lug on the lever at a place near the pivot gives a greatly accelerated motion to the piece which is in turn transmitted to the already recoiling bolt. The latter begins to move rearward more rapidly than the breech slide, while at the same instant the other bolt, formerly in a retracted position, is correspondingly shot forward.

The sudden forward motion of the counter-recoiling bolt is of sufficient force to strip a round from the feeder and cock the firing-pin spring, while simultaneously the recoiling bolt with its extractor carrying the empty cartridge case makes contact with the ejector. The latter strikes the base of the empty case pivoting and knocking it free of the gun through the ejection slot in the bottom of the receiver. As the recoiling bolt continues rearward, the other bolt approaches battery until the round is chambered and the mechanism is securely locked. At this point, if the trigger continues to be depressed, the cycle of operation begins all over again.

Chapter 14
Darne Aircraft Machine Gun

About halfway through World War I the French brought out an aircraft weapon that had been manufactured with great secrecy. The weapon was the invention of Regis Darne and his son, Pierre. Their factory was in the town of St. Etienne, located in the coal mining area lying between the Loire and Rhône valleys. At the time this company had the Government contract for manufacturing all the Lewis guns made in France, its capacity then being 5 a day. The first Darne gun was introduced in 1916 and a few were issued in 1917. It attracted the attention of the French military high command to the point that in August 1918 the factory was ordered to produce all possible Darne-type machine guns for the planned spring offensive.

With the coming of the Armistice shortly afterwards, the Darnes were requested by their government to continue development of automatic weapons with the understanding that the technical services of both French artillery and air force would furnish data on new requirements. This company bent every effort towards standardizing and simplifying the various components in order to accelerate production in the event of an emergency. This, they thought, would not only facilitate instruction in ordnance classes whereby the weapon would be comparatively easy for gunners to master, but also make easy its manufacture, thereby creating the large reserve stock of spare parts so necessary for actual combat.

For over 15 years following World War I, this company manufactured high-grade shotguns and hardware to remain solvent, but it likewise experimented on a large scale with its machine gun. At the end of this time, it not only standardized the weapon but also produced enough to issue to many French units in Africa and to several Balkan States for their air forces which subjected them to severe field tests. That they passed the rigorous conditions laid down in the official specifications is best judged by the fact these countries reordered several times.

At Cayaux in August 1932 at an altitude of 25,000 feet with a temperature of -18° C, a pair of Darne guns were mounted on a Scarff ring and the weapons fired by remote control. The test was to subject them to low temperature and exposure. Records show they functioned satisfactorily.

The weapon was gas operated, as were all French machine guns, with no provision made to regulate the amount of gas bled from the bore to the face of the piston. The company placed a port of predetermined size leading to the gas chamber and made it so that the individual gunner could not get it out of adjustment. That the largest possible orifice was used is attested by the fact that the aviation model Darne had an abnormally high rate of fire.

The weapon can be fed by both metallic strip or fabric belt, the system being so constructed that by rearrangement of parts it can be fed either right or left handed. The aviation model had both a pistol grip with a trigger device actuated by a rearward movement of the finger and a synchronizing device that mechanically released the sear and controlled the firing of the weapon through the propeller. When the gun is fired and pressure is exerted on the piston by the gases, this piece is driven forcibly to the rear. At the same time the gas piston starts to compress the driving spring. If the trigger bar continues to be held down, the piston cannot be caught by the sear at the end of its backward movement and the driving spring reacts in turn to throw the whole group forward, repeating the firing cycle.

These alternating movements of the gas piston shuttle the firing mechanism in the longitudinal slideways of the receiver. The breechblock covers the upper solid part of the gas piston of which it is an integral part. The rear spur of

Darne Aircraft Machine Gun, 7.5 mm. Dual Flexible Mount.

this piece is set in a recess corresponding to the aft end of the upper portion of the piston. When the latter moves forward under the impulse of the driving spring, the sliding movement of the recoiling mechanism in that direction is stopped at the end of its slideway. The piston with attached firing pin continues on its course.

The projection comes in contact with the corresponding cam on the breechblock which is opposite it. The breechblock is thus jacked up at the rear and held in this position placing the piston in alignment necessary for its forward movement. This rising of the breechblock brings it into its seat in the oblique recess made above its upper portion.

The rear face of the breech is then buttressed against the supporting part at the aft end of the recess securely locking the mechanism. This piece is specially heat treated as it has to stand the shock which will be produced by the exploding powder gases. The locking mechanism thus raises the bolt in the rear making way for the gas piston to continue its forward movement. The latter is provided in the front portion of its solid part with a firing pin which comes forward to strike through the opening in the bolt face against the primer of the cartridge. The round cannot be fired until the gas piston has raised all parts into battery and the arm consequently is safely locked.

As pressure builds up in the bore and the piston is thrust backwards by the impact of the gases, one of the two cams borne on its upper solid part comes in contact with the lock. The effect is to bring the rear of the breech into the axis of the upper slideways of the receiver.

As the unsupported breech no longer opposes the sliding movement, the piston pulls the breechblock rearward, at which point the extractor withdraws the empty cartridge case from the chamber. In this recoiling movement the breechblock strikes near the end of its course, the rear stud of the ejector forcing it to pivot. This oscillation brings the front stud into the path of the cartridge case, throwing the empty case through the ejection slot in the receiver. The piston and its components then reach the end of their course, at the same time compressing the main driving spring.

During this part of the cycle the cartridge carrier has previously seized between its claws a cartridge at the base of the case, and pulling it to the rear extracts it from the belt. At this moment the rear face of the claws is buttressed around the rim of the incoming round. During the first fractional inch of pulling the cartridge, the bullet pusher, actuated by its strong spring, presses against the front end of the bullet and follows it as it moves backwards. Thus the effect of inertia is neutralized with a view of avoiding

Darne Aircraft Machine Gun, Model 1918, Cal. .303.

the malfunction commonly known as a short round. After having exerted its action, the bullet pusher is cammed forward again by the transverse movement of the next cartridge sliding into the feed slot. As soon as the point of the bullet has passed into the clear, the bar actuated by the cartridge carrier spring raises the incoming round at its middle part. The cartridge at this point assumes an angle of approximately 45° with the point of the bullet resting a little above the axis of the bore. During this final movement the front boss of the feed cam strikes the free end of the small rod carrying it towards the rear and the round is chambered. The action in battery is ready to repeat the cycle if the trigger remains depressed.

The Darne has often been erroneously referred to as another type of Hotchkiss machine gun because of its physical appearance and the fact that both are gas operated. Many things in the basic design of the Darne machine gun, however, are to be found only in this weapon. The feed system is indeed unique both as to position and method of operation. The two claws attached to the gas piston withdraw the incoming round from the feedway after it has been pushed from its link by an odd device that cams the cartridge positively back by pushing with great force on the nose of the bullet. They also prop the round up on a 45-degree angle, with two fingers attached to the gas piston, without relinquishing its hold. This unusual method of feeding has many good features, such as performing all its necessary functions on the powerful recoil stroke of the piston where there is surplus energy. The design also makes possible a short bolt stroke. These two features contribute much to the weapon's high rate of fire, that has been vouched for by competent American observers to be as high as 1,700 rounds a minute when the 7.5-mm rifle cartridge was used.

The French mania for economy may have been the biggest factor in the lack of success of this gun, as the Darne Co. did everything possible to cheapen its construction, offering as an argument the short life of an airplane which made it foolish to build a gun that involved too much expensive machining. These guns were furnished to the French Government in 1931 for 700 francs, then equivalent to $28. Such a price was more in keeping with the cost in America of a good single-shot rifle than it was for an aircraft machine gun. At this attractive price the company, in the period from 1918 to 1931, sold 11,000 machine guns in all. Serbia got 2,500, Italy 1,000, Spain 1,200, Brazil 150, and the remainder were delivered to France at a rate of 10 a day.

The aircraft version was also adopted by Lithuania following a competitive test held in December 1934. In May 1935 a British commission arrived at the Darne plant to witness a test of the guns for the purpose of buying license rights to manufacture them in Great Britain. The weapon passed the French test but failed at a later trial in England.

The Darne Co. took great pride in the fact that the weapon did not have a single piece of forged steel in its construction, making possible production of an inexpensive yet reliable gun.

A tourelle magazine was also designed for

Darne Aircraft Machine Gun, 7.5 mm. This Is a Fixed Gun for Synchronizing.

aviation use, having the unusual capacity of 500 rounds available for continuous fire. The double-barrel Gast machine gun, which was then held in such high esteem by both German and Allied ordnance officers, had a maximum cyclic rate of fire of 1,800 rounds a minute. By mounting two Darne guns side by side to resemble the much heavier Gast, the arrangement gave a minimum of 2,400 shots per minute. The company was proud of this system of mounting and catalogs appeared in many languages showing its alleged superiority.

Several hundred guns were sold to Spain which were used in the Moroccan campaign. On these weapons was installed the load indicator, a device that showed the gunner not only if the gun was loaded but the amount of ammunition left in the feed box.

Following what it considered the success of the aircraft model, the Darne Co. then developed a light machine gun, a heavy one for infantry use, and an antitank automatic gun chambered for the 11-mm military cartridge.

All Darne machine guns were rough in appearance, being produced in this manner intentionally since refinement in appearance would only add to the cost. Cheapness and ease of manufacture were the main points considered in their design.

The barrel was made with exterior projections and the gas port had a conical exit into which the gas tube fits. The piston had only three bearing surfaces, one at the front where the force of the gas was taken in and two at the rear where it fitted loosely in the guides of the receiver. The feed mechanism was one of the most positive known, being actuated by the recoil stroke of the gas piston. The two fingers holding the cartridge in position for chambering were indeed unique.

Initial extraction was employed to loosen the empty cartridge case before the extractor snatched it from the chamber. Ejection also was satisfactory. The heavy bolt was securely locked during firing by a shoulder on the gas piston, camming the rear of the bolt up into the locking recess milled into the receiver body. Had many of the ingenious methods employed in this cheaply constructed weapon been given refinement and placed in a well-designed receiver, it no doubt would have been among the best of the gas-operated type.

The Darne Co., in 1935, also tried designing a 25-mm aircraft motor cannon with rounds being fed to it from a belt with metal clips. This weapon was placed in secret status by the French Government and, when France was overrun by the Germans in World War II, it, with all data on its performance, fell into enemy hands. This weapon was reputed to have fired at a rate of 750 shots a minute. Experiments were also made with a triple 7-mm rifle caliber machine gun, but it, like the 25-mm automatic cannon, never got beyond the prototype stage.

Darne machine guns have been mentioned both favorably and otherwise, but on two things everyone is agreed. The most outstanding features about the factory were the outmoded machinery the company used and the poorly illuminated, cramped quarters in which 400 men had to work.

Darne Machine Gun, Model 1929, 7.5 mm.

Chapter 15
Beardmore-Farquhar Aircraft Machine Gun

The Beardmore-Farquhar machine gun was one of the lightest machine guns ever constructed, weighing only 16 1/4 pounds with a 77-shot drum magazine attached and loaded with the .303 British service cartridge. This weapon was the invention of Col. Moubray Gore Farquhar, of Birmingham, England, and was manufactured by Messrs. William Beardmore & Co., also located in Birmingham.

Many special features were claimed by the promoters, such as its cheapness to manufacture, the practically jam-proof mechanism, perfect breech locking and a safety feature making it impossible to fire the weapon without the breech being securely locked. It was recommended that no oil be used on the highly polished close-fitting mechanism, thus making it an ideal weapon for an observer in a plane where great altitude gummed up the working parts of similar firing mechanisms that demanded lubrication. The makers of the gun also claimed the heat of the barrel did not affect the other parts, as they would continue to function properly even if the barrel was red hot during the entire time of operation.

The weapon was similar in appearance to other drum-fed observer guns that had been used so successfully by the British Royal Air Force during World War I. The manufacturers, however, considered it to be a real improvement over similarly constructed ones because of its unusual method of operation.

The most unique feature of the gun is the extensive use of springs for its operating energy. It is placed in the unusual classification of being actuated by both gas piston and spring. The power of the exploding powder charge does not act directly on the bolt's unlocking mechanism but compresses and stores up spring energy until the bore pressure drops to a safe operating limit. The bolt is then unlocked by the smooth action of the strong spring, which gives positive unlocking without the jarring effect of a straight gas-piston-driven mechanism. The piston is contained in a cylinder which is fastened to the barrel and connected to the bore by a drilled orifice. The main driving spring is housed in the front end of a part known as the spring tube, with a kind of sear device also located in this part. The front of the housing is held in position by a tube cap and fore end piece.

The design of this peculiar weapon also has what is called the bolt-closing spring. It is placed around a central rod, and when installed, is located at the rear of the spring tube underneath the barrel.

When the cartridge is fired and the bullet passes the orifice in the barrel, gas is bled into the gas-cylinder chamber forcing the piston rearward and compressing the main spring until it is held in this position by the catch or sear. The spring is thus compressed between the catch and head of the tube. It remains compressed until the resistance to turning the bolt head, caused by the pressure of the gas in the chamber working on the locking lugs against the body, is so reduced that it can be overcome by the strength of the compressed spring.

The main spring held securely by the sear, with its firm abutment against the holding washer, extends rearwards carrying with it the bolt carrier to which the bolt is attached. The force of the main spring, upon opening the bolt, extracts and ejects the empty cartridge case and compresses the bolt-closing spring. The main spring, now being fully extended and no longer pressing against the sear and catch, disengages, allowing the now-compressed bolt-closing spring to start counterrecoil movement of the parts. They in turn strip a fresh round from the feeder and return the main-spring-sear washer and piston to battery position and in the final movement forward lock the bolt securely to the barrel.

The breech action is of the straight-pull type

Beardmore-Farquhar Aircraft Machine Gun, Cal. .303.

whereby the bolt carrier slides in slots outside the body. The carrier is provided with an internal cam slot which engages the bolt arm. The bolt is composed of a non-rotating cocking piece and a rotating bolt head. The locking lugs are at the front of the bolt head and engage with corresponding resisting shoulders located in the receiver directly behind the chamber. When the lugs have entered the body, the arms engage its face. The bolt arm, continuing its forward movement, is turned by the cam slot until the lugs engage the resisting shoulders and the bolt is securely locked in battery. The extractor, in its final movement forward, cams itself over the rim of the chambered round.

The ejector consists of a pin supported by a spring and housed in the bolt, with the point of the ejector pin protruding through the face of the bolt. When home over the face of the cartridge, the ejector pin is depressed flush with the bolt face. But if the empty case has been extracted far enough that the front end is not supported by the chamber, the ejector pin jumps smartly forward throwing and pivoting the empty case through the ejection slot in the left side.

The bolt always remains locked in the Beardmore-Farquhar until the force required to unlock it is less than the strength of the compressed main spring. This makes it impossible for any extra amount of gas pressure to hasten unlocking, or for that matter, affect the operation in any way.

The feed mechanism is also very interesting in that it is a rotary affair holding two layers in the drum. The cartridges are put under spring tension and likewise indexed and stopped by a spring-loaded catch. The entire drum can be unloaded manually in an instant by depressing the two feed stops simultaneously.

It was claimed that the operating mechanism was not as likely to heat up from barrel heat as other guns of similar design. Since the connecting parts of the metal were of reduced section or skeletonized to a great degree, the heat was thus confined only to the barrel.

To simplify further the construction of the weapon, there were no radial fins or like

arrangements on the barrel for cooling purposes. On an official test the weapon fired 640 shots in rapid succession without jamming from overheating. The manufacturer contended a weapon of such design would never be called on in air combat to equal or exceed this. Therefore, he could not see the logic of adding to the weight by placing more metal into the barrel.

The inventor demonstrated on every possible occasion the good features of his weapon and personally fired it. The colonel must have been a good marksman as well as an ingenious inventor, as he once placed 75 hits on a target with a one-drum burst, at the required military range distance.

On 14 November 1919 the Royal Air Force gave the Beardmore-Farquhar machine gun an official aerial test. The weapon was presented by Colonel Farquhar and immediately fitted in a Bristol fighter machine on a Scarff-ring mounting. Firing trials were then carried out at high altitudes. The pilot was Flight Lieutenant Rea and the gunner, Flight Lieutenant Pynches. Twenty rounds were fired automatically at 4,000 feet and the gun functioned perfectly. At 18,300 feet, 320 rounds were fired at various angles of elevation, depression and training.

Up to a maximum firing position it was reported the gun was very easy to handle at any desired position and no difficulty was experienced in shipping and unshipping the rotary magazine. The rate of fire at the maximum altitude attained, 18,300 feet, was figured at 430 rounds per minute, which was considered the limit for ground firing. The angles of elevation, depression, and training in a firing position were the same as obtained by other guns that had been previously tested on the same mounting.

The cartridge cases were ejected about 6 feet out of the gun and carried by the slipstream past the fuselage of the aircraft. Only in one instance did the ejecting of an empty cartridge case fail. This occurred in the last round of the first magazine when firing at the maximum elevation in altitude. The cartridge case was eventually extracted by alternately withdrawing and releasing the bolt about 20 times. The case was unfortunately ejected overboard but it was thought by the gunner that the jam was due to faulty ammunition, probably to an over-sized rim.

No other stoppages or jams occurred during the remainder of the test. During the flight, loaded magazines had been placed flat on the floor of the aircraft and the vibration released the spring-loaded cut-off in the feed which opened it and emptied the ammunition on the floor. Ordinarily during flight these magazines or drums would have been stowed on a stud. It was agreed that excessive vibration fouled the cut-off projection during the stowing of the magazine, thus causing the loss of the ammunition.

The authorities in charge of the test recommended that a stop on the magazine be placed immediately behind the cut-off to eliminate the above possibility, as it was sometimes customary for pilots to carry the drums on the floors of their planes. It was also suggested that the flat steel rod connected to the reciprocating breech mechanism should have a guard over it, since it was possible for the gunner's fingers to be in the

Beardmore-Farquhar Aircraft Machine Gun, Cal. .303.

way of the recoiling breech. The guard would also prevent oil thrown out by the engine from getting into the working parts of the weapon. Another recommendation was that an additional handling advantage could be obtained by adopting a round section handle projecting to port about two inches and bent downwards to form a hand grip instead of the present method of handling.

The testing board's conclusions were that the gun compared very favorably with other weapons of similar design, with the additional advantage of having less kick. The rate of fire was not quite as high as similar designed guns. The weapon was lighter and less liable to jams. A much more extensive trial would however be necessary before a definite conclusion could be arrived at on the foregoing points as well as the behavior of the gun after ordinary long service usage. It was further noted that the 77-round drum could be detached and a 5-round magazine, using the infantry cartridges in their present clips, could be placed on in a matter of seconds, converting it quickly from an aircraft gun to a lightweight automatic rifle for infantry use. The rapid-change barrel system employed by this weapon was also commended.

After tests conducted at a later date the British Government decided that the weapon was not so much superior to others of similar nature already in existence as to justify its over-all adoption as the Royal Air Force observer gun, and with this decision all work and development stopped.

Chapter 16
Brixia Machine Gun

The Brixia machine gun Model 1920 was devised by engineers of the Brescia Metallurgical Works, formerly the Tempini-Brescia Company, producers of 40,000 Fiat machine guns under Italian Government contract. From their background and a comparative study of all known machine gun mechanisms, they developed what was considered an improvement that "fulfilled in all respects the requirements suggested by experience of five years of war." In the weapon's design special attention was paid to: (1) Lightness, yet reliability of construction; (2) simplicity and solidity of component parts; (3) maximum ease in stripping and assembling; and (4) safety and ease of operation.

One of the Brixia's most unusual features was the complete housing of the recoiling parts to prevent introduction of sand, dust or other foreign matter that would hinder operation. In the event of premature explosion of a cartridge the operator was fully shielded by the encased receiver. The method of feeding was also claimed by the producers to be much simpler than that of other machine guns. The gun was fed automatically by metallic loaders formed into rectangular boxes and attached to the receiver.

There was also incorporated in the weapon a means of regulating rate of fire while the gun was in action. Cooling was accomplished both by air and water. When water cooled, the conventional jacket was used, but in the aircraft model the barrel was cooled with radiation of the flanges that were an integral part of the barrel. For the water-cooled version the barrel was

Brixia Machine Gun, 6.5 mm.

Components of the Brixia Machine Gun, 6.5 mm.

slightly conical with cylindrical adjustments at the end for sliding it in and out of the packing gland that was located at the fore and aft end of the jacket. The barrel was copper plated at the two points of contact, to prevent rust from forming at these spots.

Another selling point brought forth by the manufacturer was that all parts were interchangeable, allowing the gunner to make repairs in the field, merely by changing components. Great emphasis was placed upon the fact that this could be accomplished without the aid of tools.

The rifling depended on only four grooves to the right to put rotation on the 6.5-mm bullet. The breech end of the barrel had a projection that came to rest in the corresponding recess of the receiver. The designers believed that four lands and grooves were sufficient to give the bullet all the rotation needed and that the resulting reduction of friction would prevent overheating and enable longer bursts to be fired.

The recoiling mechanism consists of the bolt, barrel, barrel extension, and what is called the "otturatore," or recoil catch. The bolt has a circular section and attached to it is a rectangular projection which moves forward during counter-recoil and comes to rest in a corresponding slot milled in the upper part of the receiver. The projection of the bolt is constructed in two pieces. In the upper part two holes house movable fingers which serve not only to lock the boh but to regulate rate of fire.

Also in the receiver body is a transverse slot for the passage of the recoil catch which buffs the recoil movement of the barrel extension after being unlocked from the bolt. In the center of the projection a recess, through which the breech

lock passes when in battery, rests upon the rear face of the projection. Directly above it is a hole to house the safety spring. The latter holds the cocking lever up in line with the slot cut for its travel when the breech lock is removed from its path by being in the locked position.

In addition, a slot is cut high up on the left side of the receiver for the ejection of empty cartridges and an opening on its lower right side provides for the introduction of ammunition by means of a magazine. The ejector is a portion of the receiver made to butt into the base of the empty cartridge. It recoils rearward while being held by the extractor, which is peculiarly located on top of the bolt.

The trigger arrangement consists of a button, the movement of which is limited by the rate-of-fire regulator, a goose-neck-shaped bolt inserted and held transversely in the receiver. While in its various positions and in conjunction with the trigger mechanism, it lengthens or shortens the travel of the recoiling parts. This unusual firing device is provided with a thumb piece that protrudes from the left side of the receiver and, by means of finger pressure, controls the speed of operation. The regulator itself is an eccentric bolt. The cylindrical part is moved along an axial plane while the periphery of the other half has two grooves which are at variable distances from the axis of rotation, and in which rest the tops of the middle fingers that serve to accelerate the recoiling action rearward. Pushing down the regulator on the left side of the gun with trigger button depressed at various levels controls the distance of movement fore and aft.

To operate the Brixia, a loaded magazine is inserted in the corresponding slot until the loosening of the restraining catch shows it to be completely seated. With his right hand, the gunner draws the charging handle attached to the loading bar back smartly for the maximum distance and releases it. The recoiling parts are then sent forward with great speed by the compressed driving spring. On the way to battery they strip from the magazine attached on the right lower side a live round and by the employment of two

Brixia Machine Gun, 6.5 mm.

lower flanges guide the cartridge into the chamber. When this is accomplished, the loading bar carried by the recoiling parts returns to its original position, locking itself on its catch. The breech lock, being pushed forward from the breech, is inserted between the loading bar and recoil mechanism to insure complete locking before the act of firing.

The firing pin, held back by the front part of the cocking lever, is now in the cocked position. By pushing forward on the trigger button, the round is fired. The pressure of the exploded powder charge causes the recoil of barrel, bolt, and bolt extension all locked securely together for a distance of about 5 millimeters. At this point the weapon begins to unlock as the breech lock turns over backward and by doing so acts as an accelerator.

After the short recoil the barrel extension is stopped by a buffer. The bolt, now unlocked from the barrel, continues to the rear, carrying the empty cartridge case gripped at the top of its rim by the extractor. At a distance slightly greater than the over-all length of the incoming cartridge, the base of the brass case hits the ejector projection that is an integral part of the receiver and kicks the expended case out the upper left side of the receiver. The recoil movement is stopped by a buffer housed in the back plate and under the influence of the driving spring and the buffer starts the operating parts into counter recoil. The magazine-fed cartridge slips into position in the carrier and is lifted up in line for the incoming bolt to strike and thrust it into the chamber.

The bolt is now locked to the barrel and extension and the firing pin remains in a cocked position provided the firing button is not depressed. In order to execute continuous fire, the firing lever must remain pressed down as far as possible. The lever is then placed at the bottom of the inclined face and will allow the weapon to fire automatically. When so held, a maximum rate of 600 shots per minute is attained.

Chapter 17
Mendoza Light Machine Gun

Señor Rafael Mendoza, a foreman at the National Arms Co., Mexico City, D. F., in 1920 started the design and development of a light machine gun. Twelve years later he felt his working model was at a point of perfection that would justify testing by the Mexican war department for official adoption.

The gas-operated weapon had a non-recoiling air-cooled barrel and a 30-shot spring-loaded double-column magazine. Its maximum rate of fire was 500 shots a minute and its weight was 18½ pounds. It could be fired both semi- and full automatic, the bolt remaining open after full trigger was released. The magazine was located on the top right side of the receiver which did not necessitate the offsetting of the sight system.

The standard Mendoza gun came with bipod but it could be instantly adapted to antiaircraft mounting. The barrel, which had cooling fins, was chambered for the Mexican infantry Mauser 7-mm rifle cartridge and could be changed in a matter of seconds when necessary. A flash hider was always incorporated in the design. Barrel removal in the field was accomplished in the following manner: First the gun was cocked, after which the barrel latch on the forward end of the receiver was pressed in; the large lug holding the barrel to the receiver was freed; and the barrel could then be pulled forward.

The weapon was constructed with only 22 working parts. This fact alone showed great skill in design and planning, as such simplicity eliminated many malfunctions.

In October 1932, at the Rancho del Charro, D. F., the Mendoza, along with several other light machine guns, was officially tested under strict security by a board of officers representing the Mexican Government. They were greatly impressed by the performance of this Mexican-designed and produced light machine gun. After consulting with Mendoza, the government in June 1933 invited M. H. Thompson, a well-known New York engineer who had previously

Mendoza Machine Gun, 7 mm, Right Side.

done ordnance work for Mexico, to visit the National Arms plant for refinement of the weapon. This was done and in August 1933 the president of the republic ordered the limited manufacture of the improved gun for further test and experimental purposes.

This work was carried out in great secrecy, even to its adoption as the Mexican Army's standard light machine gun in December 1933. On 6 June 1934, after all tests and experiments were successfully concluded, the National Arms Factory was ordered to proceed with full production on these efficient lightweight weapons. The government took over Mendoza's invention, paying him well both in money and honors and applied for a patent in the United States in his name. The first twenty guns were issued to the 48th Infantry Battalion, then stationed at Chapultepec.

The Mexican Commission of Military Studies requested that as soon as delivery was made of the Mendoza machine guns they be distributed to the tactical units, as follows: 18 guns to each cavalry regiment and 24 to each infantry battalion. They were to replace the automatic weapons with which the troops were armed at the time, namely--Hotchkiss, Colt, and Vickers, all of which were eventually withdrawn and put in reserve as the new Mendozas were received.

After the army had already been armed secretly with this weapon, the Mexican war department published the following bulletin:

"Order No. 42, 6 December 1934.

"By order of the Substitute Constitutional President of the Republic dated 31 October 1934 the Mendoza machine gun rifle ('fusil ametrallador') and the Mendoza light machine gun are hereby declared regulation in the Mexican National Army and Navy. The War Department has already taken the necessary steps that the corresponding armed units may be equipped with this material with as little delay as possible."

The weapon has many advanced features, although the main principles of operation are as old as automatic firing mechanisms. Basically and from an operational standpoint it is a Lewis action but this system is noticeably improved by incorporating a double cam slot. The device did much to equalize the torque and consequently reduce the locking friction, so common when the bolt face is held securely behind the cartridge base.

Although the gas cylinder greatly resembles the Hotchkiss, the conventional method by which it encloses the piston is not employed. Instead, a cuplike arrangement in the gas assembly houses a short and separate piston which after a brief stroke rearwards allows the powder gases to dissipate into the air. This is exactly the

Components of the Mendoza Machine Gun.

reverse of the ordinary gas-operated firing mechanisms.

The selector switch is located on the left side of the receiver above and slightly in front of the trigger guard. A most unusual cocking method is employed. On the left side near the end of the firearm projects a small piece to be pulled by the left hand directly to the rear until the sear engages and holds the gas piston and bolt in a retracted position.

The firing pin is unique in construction. Driven forward into the primer of the cartridge by its attachment to the bolt extension, it is made with two identical protrusions so that when a tip is broken off it may be remedied simply by reversing the ends.

Another interesting feature is the ejector, a long finger pinioned in the right side of the receiver and an integral part of an assembly which includes a bolt-hold-back device. The rear end of the bolt is used as a cam on the right side so that as it moves to the rear it noses the ejector and hold-back device out of the way. But as the aft end of these members is struck, the cammed surface forces the ejector's nose back into a slot in the forward part of the bolt, while the nose of the hold-back moves into a notch on the bolt's right side.

No provision is made for head spacing as neither barrel nor receiver has the necessary threads. The barrel is simply inserted into the receiver, its rear end being slotted to take the locking key. The latter also passes through the receiver and is held by the same retaining pin. On the last shot a three-cornered stop attached to the magazine follower protrudes past the lips of the magazine into the receiver, blocking the movement of the hold-back pawl. Thus the empty magazine holds the bolt to the rear with the expenditure of the last cartridge. When a fresh magazine is inserted, it releases the rear sear, at the same time letting the bolt come forward just enough for it to engage the notch in the actuator. This makes instant action possible with the weapon after a loaded magazine has been placed in position.

To fire the Mendoza Model C-1934, the operator, generally prone, inserts a loaded magazine into its locking recess on top of the receiver. If automatic fire is desired, the selector switch is moved forward from its safety position. The charging handle is pulled with the left hand all the way to the rear until the holdback sear en-gages its notch in the bottom of the bolt extension, the short gas piston remaining in its housing under the gas port.

Mendoza Machine Gun, 7 mm, Left Side.

Being cocked and with a cartridge in place for stripping, the weapon is now ready to fire. A pull of the trigger to the rear disengages the sear and the operating parts are driven forward by the tension of the compressed driving spring. As the bolt face passes the rear of the double column-type magazine, it pushes the first cartridge from the lower right edge of the magazine as the extractor cams itself over the cannelure of the cartridge. When the cylindrical bolt has chambered the round and stopped, the eight locking lugs of the bolt are in line with the fixed lugs. The bolt extension, still three-fourths inch from battery, continues forward, rotating the bolt and locking it to the receiver.

The rotation removes the obstruction from the path of the firing pin. This piece, attached by a fug on the bolt extension projecting vertically through the firing pin and bolt, can now be driven forward to fire the round. As gas pushing the bullet through the bore reaches a port 11 inches from the breech end of the barrel, a portion is released into the short gas piston. The bolt extension moves rearward about three-fourths inch before its lug strikes the cam in the bolt slot. The firing pin, which is a cylinder with a point on each end, starts backwards with the actuator.

The continued movement of the extension rotates the bolt, unlocking it and carrying it to the rear. The extractor in the left side of the bolt body withdraws the empty cartridge case from the chamber. As the bolt and bolt extension keep on, the ejector contained in the right side of the receiver strikes the cartridge case at its base, knocking it through the left side of the slot in the receiver. The full energy of the moving parts is absorbed by compression of a driving spring. At the completion of the recoil stroke the whole assembly is started into counterrecoil movement to feed, lock, and fire each round.

Mexican military authorities were justly proud of the Mendoza, as it was very efficient and served the purpose for which it was designed. The Mexicans have always been admirers of fine weapons and their history includes inventions that have contributed much to the art and development of automatic arms. On this list Rafael Mendoza's contribution ranks high.

Chapter 18
Chatellerault Machine Gun

The French, ending World War I with the realization that they had been armed throughout the conflict with the worst automatic weapon ever designed, the Chauchat, were the first of the Allies to adopt a post-war machine gun. This new arrival was the Chatellerault, named after one of the French Government arsenals, Manufacture d'Armes de Chatellerault. It was in design very similar to both the Berthier and the American (Browning) B.A.R., having many Features of each.

It first made its appearance in prototype stage in 1921 but was not officially adopted by the French Army until 1926; and then only after many modifications had been made on the original, giving it even more Browning characteristics. About the only basic difference was the employment of a box magazine holding 30 rounds inserted from the top that made unnecessary the forked piston used on the B.A.R.

The Chatellerault had two triggers housed by a guard, the forward one for single shot, the rear for automatic fire. A gas device, that could be regulated, worked in conjunction with an adjustable back-plate buffer to permit variable rates of fire at the control of the gunner. The top magazine arrangement made necessary an awkward off-setting of the sight.

The French had found from earlier attempts at machine gun design that their 8-mm Lebel rifle cartridge with its stubby and steep conical rimmed case was most certainly not the best-shaped cartridge for automatic use. Therefore included in the plans for this gun were drawings for a completely new round of ammunition. The result was a 7.5-mm rimless cartridge case with practically no taper on it, very similar in appearance to the Swiss Army cartridge from which it was closely copied even to the boat-tail 149-grain cupro-nickel bullet.

The Chatellerault weighed slightly under 20 pounds and was not only heavier but much more

Chatellerault Machine Gun, Model 1923, 7.5 mm.
This is a Prototype Gun, Serial Number 11.

expensive to make than the Chauchat, since the latter gun was more of a plumbing assembly than a precision-made automatic weapon.

The French, as usual, had very little money for development and production of machine guns. As it has always been a policy of theirs to encourage adoption of their own weapons by friendly powers and prospective Allies, their military attachés who were located in such countries were instructed to spread favorable reports on the performance of the Chatellerault machine gun, even before it was officially tested, and to indicate it would be available for purposes of adoption if the authorities could be interested.

In 1925 the Yugoslav Government was carrying on a competitive trial in which several European-made machine guns were tested. The Hotchkiss Co.'s entry made the most satisfactory showing and was on the verge of being contracted for when the French attaché offered the Chatellerault gun at the ridiculously low price of 2,000 francs, although it had not been entered in the competition. He intimated that it had successfully met all the demands of the French proving grounds.

A Yugoslav commission was then sent to France to investigate the claims of the Chatellerault. It was found the price quoted could not be met but, although higher than first stated, it was still considerably less than the market price of similar machine guns. The catch this time was that only a few pilot models were in existence as their manufacture on a large scale had not yet begun. The Yugoslavs, desiring an early date of delivery, called for another competitive test. This time they did not find either the Chatellerault or the Hotchkiss acceptable, the contract going for a machine gun made by another country.

A similar situation arose with the Rumanians who also sent their commission to France. However, they demanded and arranged a test before consideration of purchase. During one of the demonstrations, with one of the group firing the weapon while other members stood by, an explosion occurred in the receiver of the gun. The operator was seriously injured, as well as several others of the commission.

The Rumanians were told that through sabotage a cartridge with only enough powder barely to drive the bullet into the bore, caused two bullets to be present in the barrel for the next round, causing the regrettable incident. No explanation as to how the sub-loaded cartridge had gotten into the feed was forthcoming. The Rumanians, not quite satisfied with the explanation, in the presence of the French military attaché, produced the same condition with a Hotchkiss machine gun. The result was a swollen barrel but no violent explosion occurred.

After the weapon's adoption by the French Army, a number of explosions of identical nature took place, and quite a few soldiers were injured. As the blame could not be placed on defective ammunition, but rather on the weapon itself, it is easy to understand that the French

Chatellerault Machine Gun, Model 1924-29, 7.5 mm.

soldiers were considerably exercised over its dangerous characteristic. The troops in the field asked that they be issued the heavier and outmoded Hotchkiss in place of the Chatellerault.

The country's high command was brought to the realization that development work, if any, must be paid for by France and not by some smaller country, and that modification should be made without delay as the weapon had made such an unfavorable impression even among French troops. Necessary redesign was finally done, but, as is usually the case, once a weapon lets the reputation for unreliability, its bad name outlives by years the correction that remedies the malfunction.

It was also a severe blow to the sensitive pride of French military engineers that they did not seem able to copy either the B.A.R. or Berthier, both having proved reliable weapons, especially since, just before the weapon was tested, newspapers heralded the new gun built in great secrecy and now ready to be shown to the public for the first time. A sample follows of such advance publicity, as written by a reporter for the Paris Echo on 6 February 1924:

"A machine gun, the Chatellerault, said to be the invention of a French artillery officer . . . is equal or superior to its competitors with respect to its manner of operation, and is far ahead of them in regard to facility with which it can be handled and its principles taught to recruits-factors which are more and more important to recognize owing to the short time of military service and the considerable amount to war material, the handling of which all has to be taught to recruits . . . French arsenals are now working overtime to supply a large part of the French infantry with the new Chatellerault automatic rifle. A soldier can fire 30 shots from one burst from the shoulder with the new rifle and the French authorities consider it the most effective weapon of any army of the world. Eventually every French soldier will carry the new rifle."

It later came to light that nothing was basically wrong with the design of the weapon. The main fault lay in the pressure brought to bear by the two government arsenals, Chatellerault and St. Etienne, on high officials to have all developments done at these two army-controlled factories. It was pointed out by personnel of these government plants that they had successfully produced weapons for the army since their date of establishment. But money always being a hi factor, these places were constantly restricted by their lack of appropriations, making it questionable whether superior metals and propel heat treatment were always used.

The phases of operation with this machine gun are divided into rearward and forward movement. The stages that take place on the rearward movement are compression of the driving spring, action of the gas, movement of the bolt and the slide to the rear, unlocking, withdrawal of the firing pin, extraction of the empty cartridge case, ejection of the empty case, and cocking. The operations that occur on the forward movement are decompression of the recoil spring, feeding, locking, and firing.

To fire the 1924 model Chatellerault, the operator first attachés a loaded magazine in position and pulls smartly rearward on the charging handle until the gas piston and bolt are held in a cocked position by engagement with the rear sear. If automatic fire is desired, the selector placed on F (Fire) and the rear trigger pulled, releasing the sear which allows the compressed driving spring to thrust the bolt and gas piston forward. The feed rib on top of the bolt enters between the lips of the magazine and shoves the bottom round forward. The nose of the bullet strikes the bullet guide in the top front portion of the receiver, guiding the incoming round down towards the chamber. As the slide and boll continue forward, the base of the cartridge is forced by the magazine spring down onto the face of the bolt behind the extractor, thus aligning the round with the chamber.

The nose of the bullet has now entered the chamber which acts as a guide from there on until the cartridge is fully seated. When the slide is three-eighths inch from being fully forward the bolt strikes the bridge of the receiver stop ping its advancing movement. The slide, how ever, continues on and the lower bolt link pin moves forward with the slide, causing the boll links to rotate around the upper bolt link pin The bolt is pushed up and locks the shoulder in the rear to the top of the receiver. Before the bolt links complete their rotation, the firing pin, which is moving forward with the slide, advances

Components of the Chatellerault Machine Gun.

through the bolt face striking the primer of the cartridge.

The powder charge having been ignited, the bullet starts forward under pressure of the expanding gases. When the bullet reaches a point four inches from the muzzle, the gases pass through a port in the bottom of the barrel into a cylinder housing the gas piston. The action of the gas is that of a severe blow on the head of the piston, moving it back approximately three-eighths inch, after which the gas escapes through slots in the gas-cylinder tube. During this movement the piston and slide move to the rear.

This action tends to pull the bolt down at the rear out of engagement with the locking shoulder in the top of the receiver. The bolt and slide are now free to move to the rear. During the first quarter inch unlocking movement there is no movement of the bolt, but the slide and the gas piston withdraw the firing pin from the face of the bolt. During the last eighth inch movement the bolt moves back, slowly pulling the empty cartridge case free in the chamber before unlocking. This initial extraction takes place while the bolt links are rotating and the bolt is dropping down from in front of the locking shoulder.

With the continued rearward movement the empty case is pulled out of the chamber and held against the face of the bolt by the extractor. When the mechanism has traveled approximately five inches, the rear left portion of the base of the cartridge strikes the ejector which is an integral part of the buffer housing. This forces the empty case to pivot around the extractor and fly out through the ejection slot cut at the right of the receiver. At the termination of the movement the rear of the slide strikes the sear buffer compressing its release spring.

When the sear buffer release moves back, it allows the buffer plunger spring to force the sear up and catch the slide, holding it to the rear. This occurs only in semiautomatic fire.

In full automatic fire the slide strikes the sear buffer release which flies back compressing its spring. In this case the rear of the sear has locked the buffer down so that it will not catch the slides. Therefore the slide goes back and forth over the sear and its buffer, never making

Chatellerault Aircraft Machine Gun, Model 1934-39, 7.5 mm, Fixed.

contact until the pressure on the trigger is released.

The safety is shaped so that, when turned to S (Safe), the two ribs on its shaft prevent either or both of the triggers from being pulled. When set on F (Fire), the two ribs are freed allowing either trigger bar to release the sear.

The dual-trigger system is very unique. When the rear trigger is squeezed, it rotates on its pin camming the front end of the sear up and forcing it to rotate, thus bringing the rear of the sear down. This action compresses the sear spring and disengages the sear from the slide, allowing it to go forward under the tension of the compressed recoil spring. This action constitutes full automatic fire.

When the front trigger is squeezed, it rotates on its pin. A disconnector is attached directly to the trigger. Its rotation causes the front end to be depressed, which forces the disconnector up against the under surface of the front of the sear.

When pressure on the trigger is released, this action forces the disconnector down against the forward face of the sear. It is thus snapped out of engagement with the trigger, permitting single shots to be fired.

In order to utilize the Chatellerault for other than infantry use, the mechanism was modified for feeding with belted ammunition in lieu of the spring-loaded magazine. Further redesign resulting in faster operation made it adaptable for aircraft use. These changes made their appearance in what was designated the Chatellerault Tank, Armored Car. Fortress, Model 1931. Essentially the gun was the same as the 1924-29 models with the exception of better heat treatment of parts and the substitution of a huge magazine-driven feed for the clip.

The tank- and armored-car gun had a post and feed drum somewhat like the Lewis projecting horizontally from the right side plate only. For fortress use only, as in the Maginot line, the same feed could be fastened on either the left or the right side with ejection through the bottom of the receiver. The weight of the gun as 36 pounds and the empty drum weighed ten pounds. These figures show the unusual weight of the drum in relation to the gun. Its capacity of 150 rounds naturally made it much more out of proportion when loaded and secured to the side of the gun.

For fortress use, the Chatellerault had as an accessory an unusual cooling device that operated from the recoil and counter recoil of the bolt to inject from the chamber end a small jet of water into the barrel between extraction and loading. The French kept this feature secret, claiming that from a fixed position like the Maginot line where water was available they could fire bursts of unheard-of lengths without overheating the barrel.

After the 1931 model had definitely corrected the bad features of the 1924-29 gun, the French air force, in seeking a lightweight high speed gun, ordered the Chatellerault Arsenal to improve the design further. In a relatively short while the Chatellerault Aircraft Machine Gun, Model 1934, A, TO and 39, was produced. Again it was basically the same as previous models. The "A" was for "Aile" or wing mounting; "TO" for tourelle installation, both drum fed; and the "M 34/39" was a belt-fed version for wing mounting.

The rate of fire on the aircraft guns was officially given as 1,500-1,600 rounds per minute but American representatives in France credited it with not more than 1,300 rounds a minute. The 1934 version had a much longer feed post than the Fortress model, since the magazine held 500 cartridges. The circular feed was gear driven by the gas action of the gun, with a ring gear encircling the upper portion of the magazine which had the abnormal depth of 16 inches in order to accommodate the 500 cartridges. The ring gear was attached to a rack that engaged teeth on the body of the gas piston. To be installed in a plane, the weapon had to be placed with the left side plate down. The magazine support post attached to the right side plate made mounting on its sides difficult in fixed positions.

The French kept all work and development on the Chatellerault aircraft gun in highly classified status, but it was learned that a 1934 model had also been successfully synchronized and that a new driving spring was employed that gave results far in excess of anything previously used. The idea was by no means original since, according to M. Brisorgouil, Assistant Director and Production Manager of Chatellerault Arsenal, "the new type of spring has a life at least double that of the usual type."

He considered that "the new spring provides a radical improvement in automatic weapon functioning. The design is attributed to the Russians. It was discovered by examination of Russian aircraft machine guns used in Spain. . . . In place of forming the spring by coiling a single wire, the spring is formed by coiling three lengths of smaller diameter piano wire which have been twisted together."

Chapter 19
Madsen Aircraft Machine Gun

The Aircraft Version of the Madsen

The Danish Recoil Rifle Syndicate of Copenhagen in 1923 assigned its chief engineer, a Mr. Hambroe, the job of redesigning the existing Madsen rifle-caliber infantry-type machine gun to aircraft use. Because of its flat profile, the weapon was comparatively easy to adapt to plane installation. The only significant change made was the addition of a muzzle booster with considerable restriction in its throat and a heavy spring buffer to dampen out the shock of the accelerated recoil the booster gave to the operating parts.

The rifle-caliber aircraft version weighed 18½ pounds and had a cyclic speed of 1,000 rounds a minute. One of the main selling points with this machine gun was that it could be synchronized for fixed installations and still be light and maneuverable enough for successful flexible mounting.

The Junkers aircraft plant in Denmark, which assembled its planes from components made in Germany, bought thousands of the weapons for use in its products. This firm was German-owned but in order to operate and be free of Allied control, it had assembly plants in Denmark and Sweden. It sold fighter craft equipped with Madsen machine guns of varying calibers to any country interested.

Chambering the barrels to handle any rifle-caliber ammunition desired was comparatively easy for the Danish gun company, as it had already produced over a hundred different models

Madsen Aircraft Machine Gun, 7.92 mm, Flexible Twin Mount.

for infantry use ranging in caliber from 6.5 mm to 11.35 mm and using both rimmed and cannelure-type cartridges.

The caliber 11.35-mm machine gun had an oil buffing arrangement to slow the heavier but equally fast barrel and its extension. It too had a rate of fire officially stated as being 1,000 shots per minute. The first successful working model of this type of weapon was proofed at the company's range near Copenhagen in 1926.

The mounting of the Madsen as a flexible gun was very unusual in appearance as the shoulder stock in some form was retained. Installation was done in pairs on the conventional Scarff ring with a bar arrangement connecting the two rifle butts shaped in such a manner that the gunner could use its center as a brace for his chest.

Both triggers of the guns were operated from a single trip mechanism. The feeds were peculiarly shaped drums with carrying handles in the rear. Each gun had its separate aircraft-type ring sight so that the weapons could be operated independent of each other. Everything considered, it was a very clumsy arrangement and was never popular outside of small countries that had to have low-cost aircraft armament.

The Danish Recoil Rifle Syndicate prided itself that its fine machinery, as well as its system of shop management, were of American origin. The owners claimed that it was the only arms producing plant on the continent capable of mass production equal to that of a similar factory in America.

The cycle of operation for each model is identical. When the belt-fed automatic machine gun version is prepared for firing, the ammunition belt is started into the left side. The disintegrating links used in the feed belt are of peculiar design. The front of the link fits over the shoulder of the round which has to be pulled through it by the feeding action. The rear portion of the link is of the type known as the push-out or half-link, in that it does not go all the way around the

Madsen Machine Gun, Model 1926, 7 ram, Water Cooled.

base of the cartridge. A sharp claw of spring steel holds the case firmly until it is finally withdrawn.

Once the weapon is cocked and the first cartridge is placed under the belt-holding pawl, the large charging handle on the right side is pulled back. This action moves the barrel extension a considerable distance to the rear after the bolt rises. The pawl holding the cartridge in position is carried to the right by the camming action taking place between the barrel extension and the piece supporting the incoming round until the cartridge is forced through the feed slot in the receiver.

At this time a spring-loaded claw snaps over the rim of the cartridge. The pivoting of the feed arm actuates the claw rearward and withdraws the cartridge from the belt, positioning it in the feed trough in the top of the bolt. The pivoting lever has by now taken its place behind the round. Upon release of the cocking handle the energy of the compressed driving spring sends the lever forward. The front end of the bolt is pivoted down below the bore in the barrel. Further movement forward of this lever causes it to strike the base of the cartridge, ramming it into the chamber. The final pivot movement raises the breechblock full behind the bolt and the weapon is ready to fire.

The rearward pull of a trigger releases the large striker which flies upwards in an arc against a firing pin, detonating the primer. During recoil, the barrel, barrel extension, and bolt are securely locked for one-half inch, until the trigger bar is struck by the rear of the recoiling bolt mechanism. This frees it, allowing the striker to be forced back to the cocked position and the spring-loaded firing pin is withdrawn into the bolt body. The guide stud then passes out of the horizontal groove and travels up the top cam of the switch plate to pivot the bolt face upwards. The base of the empty cartridge case is thus uncovered, permitting the recoiling extractor to apply a sudden mechanical advantage as it strikes the lug in the bottom of the receiver. The extractor claw, in one rolling motion, not only withdraws but ejects the empty case from the chamber. The case is guided out of the receiver by the curved contour of the bolt until it falls clear to the ground.

During the last of the recoil movement the barrel extension has cammed another round into the receiver feed slot, and the pivoting feed and operating arm positions it in the trough formed by the machined recess in the top of the bolt. Counterrecoil, originating in the stored energy of the driving spring when it starts the entire operating assembly back to battery first depresses the bolt and then drives the cartridge into the chamber.

The bolt and barrel extension are then accelerated forward by this spring acting through the medium of the cammed pivoting of the radial operating arm. When the counterrecoil movement is almost completed and the base of the cartridge is fully covered by the rising of the pivoting bolt, a cam on the arm automatically releases a sear if the trigger is still held rearward. The striker again flies up to continue the cycle.

Madsen Tank Machine Gun, 7.5 mm.

Models and Users of the Madsen

Perhaps no machine gun has been made in so many different models and bought by so many countries as the Madsen. The following tabulation covers five decades of the weapon's distribution throughout the world:

Country	Model	Bore
Argentina	1910	7.65 mm
Argentina	1925	7.65 mm
Argentina	1926	7.65 mm
Argentina	1928	7.65 mm
Argentina	1931	7.65 mm
Argentina	1935	7.65 mm
Bolivia	1925	7.65 mm
Brazil	1908	7.00 mm
Brazil	1913	7.00 mm
Brazil	1916	7.00 mm
Brazil	1925	7.00 mm
Brazil	1928	7.00 mm
Brazil	1932	7.00 mm
Brazil	1934	7.00 mm
Brazil	1935	7.00 mm
Brazil	1936	7.00 mm
Brazil	1946	7.62 mm
Bulgaria	1915	8.00 mm
Bulgaria	1927	8.00 mm
Chile	1923	7.00 mm
Chile	1925	7.00 mm
Chile	1926 w/c	7.00 mm
Chile	1928 w/c	7.00 mm
Chile	1940	7.00 mm
Chile	1946	7.62 mm
China	1916	7.92 mm
China	1930	7.92 mm
China	1937	7.92 mm
Czechoslovakia	1922	7.92 mm
Czechoslovakia	1923	7.92 mm
Denmark	1904	8.00 mm
Denmark	1916	8.00 mm
Denmark	1919	8.00 mm
Denmark	1924	8.00 mm
Denmark	1939	8.00 mm
Denmark	1946	7.62 mm
England	1915	7.69 mm
England	1919	7.69 mm
England	1929	7.69 mm
England	1931	7.69 mm
England	1939	7.69 mm
Estonia	1925	7.69 mm
Estonia	1937	7.69 mm
Ethiopia	1907	7.92 mm
Ethiopia	1910	7.92 mm
Ethiopia	1934	7.92 mm
Ethiopia	1935	7.92 mm
Finland	1919	7.62 mm
Finland	1920	7.62 mm
Finland	1921	7.62 mm
Finland	1923	7.62 mm
France	1915	8.00 mm
France	1919	8.00mm
France	1922	8.00 mm
France	1924	8.00 mm
Holland	1919	6.5 mm
Holland	1923	6.5 mm
Holland	1926	6.5 mm
Holland	1927	6.5 mm
Holland	1934	6.5 mm
Holland	1938	6.5 mm
Holland	1939	6.5 mm
Honduras	1937	7.00 mm
Honduras	1939	7.00 mm
Hungary	1925	7.92 mm
Hungary	1943	7.92 mm
Italy	1908	6.5 mm
Italy	1910	6.5 mm
Italy	1925	6.5 mm
Italy	1930	6.5 mm
Italy	1931	6.5 mm
Lithuania	1923	7.92 mm
Mexico	1911	7.00 mm
Mexico	1934	7.00 mm
Norway	1914	6.5 mm
Norway	1918	6.5 mm
Pakistan	1947	7.69 mm

Country	Model	Bore
Paraguay	1926	7.65 mm
Peru	1929	7.65 mm
Portugal	1930	7.69 mm
Portugal	1936	7.69 mm
Portugal	1942	7.69 mm
Portugal	1936	7.92 mm
Portugal	1940	7.92 mm
Portugal	1947	7.92 mm
Russia	1904	7.62 mm
Russia	1915	7.62 mm
Salvador, El	1934	7.00 mm
Spain	1907	7.00 mm
Spain	1922	7.00 mm
Sweden	1906	6.5 mm
Sweden	1914	6.5 mm
Sweden	1921	6.5 mm
Turkey	1925	7.92 mm
Turkey	1926	7.92 mm
Turkey	1935	7.92 mm
Turkey	1937	7.92 mm
Thailand	1925	8.00 mm
Thailand	1930	8.00 mm
Thailand	1934	8.00 mm
Thailand	1939	8.00 mm
Thailand	1947	8.00 mm
Thailand	1949	8.00 mm
Uruguay	1937	7.00 mm

Chapter 20
B.S.A. Aircraft Machine Gun

During the latter days of World War I the British realized that with the advent of armor on planes a machine gun capable of canceling this advantage had to be developed. They first tried to raise the caliber of the very reliable .303 Vickers, which was done with questionable results. The next attempt was in January 1924 when the Birmingham Small Arms Co., which had produced the successful Lewis gun in great quantities in the war years of 1914-18, presented its design of a larger caliber machine gun somewhat along the lines of the justly famous Lewis. In fact, the resemblance was so striking that the weapon has often incorrectly been classified as a caliber .50 Lewis.

However, with physical appearance all similarity ends, for the B.S.A., as it is officially known, is a recoil-operated weapon that could be cooled by both air or water depending on the jacket used. It employed, in lieu of the metal link belt, the drum-type feed that held 37 caliber .50 cartridges. The weapon was simple in construction, and could be fired either single or full automatic. The components were very strong, and disassembly and assembly could be performed manually without the aid of tools. The need for a larger caliber free gun for observers was thought necessary as a companion arm to the forward firing ones in the wing installations.

The B.S.A. made its first appearance in 1928 and was tested by both the Royal Air Force and the British Navy. The aircraft version was cooled by radial fins on the barrel and by large holes bored in the jacket allowing circulation of air. The water-cooled gun had a conventional barrel jacket that allowed water to be pumped through the system by means of flexible hoses leading to a simple supply pump.

While the feed system was visually the same as used by the Lewis, it had a feature not to be found on any other such type of feed. The drum with but a 37-round capacity could by no means be considered adequate. Through spaces cut on top, however, the gunner could replenish his supply without interfering with his readiness for instant action, as removal of the drum from its post for recharging was not necessary. Cartridge cases were ejected from underneath the action. This was a distinct advantage for aircraft use, especially from an observer's standpoint, since the empty brass would be thrown on the floor of the cockpit and not out into the wind-stream to hit other friendly ships in a formation. Both spade grips and slide chargers could be placed on the receiver for aircraft use if desired by the operator.

To fire the caliber .50 B.S.A., the loaded magazine is placed on its post with the first cartridge positioned at the cam mouth of the magazine center. The charging handle is pulled to the rear until the bolt engages the sear holding the entire recoiling mechanism in a cocked position. The selection lever is then placed on single shot or automatic, as desired. When the trigger is pulled, the operating mechanism goes forward under the stored energy of the compressed driving spring, strips the round from the feeder and chambers it. The spring-loaded firing pin is tripped by the rotation of the bolt sleeve, locking it to the barrel. The firing pin is thereby allowed to fly forward and fire the chambered round.

The recoil action that follows the building up of the powder gases from the exploded charge finds the barrel, barrel extension, bolt, bolt sleeve, and two pieces called extension rods, all locked together for a 2 7/8-inch recoil. At the end of this travel the unlocking lug has revolved by means of an engaging cam. This causes the lug to revolve the bolt sleeve enough to unlock the bolt from the extension and barrel.

The rearward movement of the barrel is stopped by the front extension collar coming in contact with its buffer. The barrel is then brought back by its stout return spring to its

B.S.A. Aircraft Machine Gun, Cal. .50.

forward or normal position. The bolt, its sleeve, and striker all continue rearwards. The slow unlocking action permits initial extraction and when the bolt is nearing the end of its backward stroke, the front face of the end of the slot in the upper side strikes the protruding end of an ejector piece. The latter is slidably located in an inclined slot in the upper resistance lug in the bolt head and ejects the spent cartridge case in a downward direction through openings in the under side of the receiver.

In order that the breech bolt sleeve, breech bolt, and striker may be held in a cocked position until the barrel and barrel extension have reached battery position, the weapon has a safety lever device incorporated in the trigger guard frame. One lever is pivoted to the fulcrum pin of the sear, while its rear end is so constructed as to be moved by a spring into engagement with the bent on the bolt sleeve while its forward end is mounted on the fulcrum pin of the trigger. A second lever in this complicated arrangement engages a cam in the underside of the barrel extension and when the latter is returned to battery, this depresses the trigger bar and permits firing only when all operating parts are securely locked.

The inner construction of this gun is very unusual. In the sides of the barrel extension are found open-sided slots, in which move what are called resistance lugs located on the head of the bolt sleeve. Near the front end of the barrel extension piece are shoulders that engage the resistance lugs. This operation is effected during the limited independent longitudinal movement of the bolt sleeve in relation to the bolt body.

The bolt body is provided at its rear end, on its upper and lower sides, with flat bearing surfaces that engage its slideway in the barrel extension. The front end of the bolt sleeve has lugs that engage the open-ended slots formed in the sides of the barrel extension.

The hollow bolt body houses the striker which is connected to the sleeve by means of a cross bar arranged to pass through a helical slot in the body. The slot is designed to permit a limited in-

Receiver, Grip and Feed of B.S.A. Aircraft Machine Gun, Cal. .50.

dependent longitudinal movement of the bolt sleeve and striker, during which a part rotative movement is imparted to the bolt to effect locking and unlocking by the resistance shoulders in the barrel extension piece engaging the resistance lugs.

Two such B.S.A. weapons were manufactured. One was turned over to the Royal Air Force and the other to the British Naval Air Force, for testing purposes. The ammunition was the same as used successfully in the Vickers caliber .50 gun and was manufactured by the Kynoch Co. of Birmingham, which cooperated with B.S.A. to produce an adequate round of ammunition. The velocity of the 813-grain projectile was officially set at 2,600 feet per second.

The trial was held at Hythe, England, and proved very disappointing. Alter the low rate of fire, namely, 400 rounds per minute, the most criticized feature was the capacity of the drum. It was suggested that this be increased to a minimum of 97 rounds. The long travel of 2 7/8 inches before unlocking made it practically impossible to speed up the gun without complete redesign.

The 2 7/8-inch recoil travel before unlocking is an inexplicable feature on the B.S.A. This movement is the longest known for such a recoil-operated mechanism. Technically, it comes under the classification of short-recoil operation, since the travel does not exceed the over-all length of the cartridge. It remains a mystery why the British slowed down the cycle of operation with such a long unlocking stroke, as it had been proved in earlier machine guns using the same cartridge that unlocking the recoiling parts after 3/4 inch rearward travel was safe.

Its faults, coupled with the fact that power-driven turrets were beginning to take the place of the observer and his free gun in aircraft, left the B.S.A. with no future in British aircraft weapon design.

The gun is an outstanding example of what

generally happens when a machine gun that has been used to good advantage in the past for a specific purpose is copied to any extent when a weapon serving another function is needed. The Lewis gun, which was so similar in appearance to the B.S.A., was quite satisfactory as a light free caliber .303 gun for open cockpit observers. When weight was added for the large caliber, it became too unwieldy and the rate of fire was prohibitive.

Chapter 21
Breda Machine Gun

The locomotive works known as the Società Italiana Ernesto Breda of Brescia, Italy, during the emergency created by World War I, commenced production of machine guns for the Italian Government. Plans and specifications were furnished the Breda firm by order of the military authorities. The first automatic weapon so made was the water-cooled Revelli, Model 1914, the manufacturing drawings being farmed out to it by the Fiat Co., holder of the patents. Breda built a separate plant adjacent to its locomotive works which, during the war and immediately thereafter, engaged in manufacturing and delivering thousands of the above-mentioned Revelli guns.

Following the Armistice, as with other arms companies in Italy, work came to a near halt with only enough government orders for modifications on existing models to keep a skeleton force active. However, all service branches were in need of an Italian-designed lightweight machine gun for infantry and a heavy one that could be used both as a heavy ground machine gun and with a modified mechanism for aircraft installation. Such a weapon could be mounted both as a synchronized fixed gun for forward firing and as a free one for observers.

The first Breda attempts at securing the lucrative government contracts, then being offered as an inducement by General Buffi, the assistant director general of all machine gun experimental work, was the production of the Breda 1924 model. The weapon introduced at this time was chambered for the 6.5-mm caliber cartridge and weighed slightly under 20 pounds. The rate of fire was officially credited as being 500 rounds a minute. The feed system had an oddly designed magazine that pivoted for charging. The barrel could be changed instantly as it connected to the barrel extension by means of heavy interrupted threads. The rear of the receiver was round while the center part over the feedway was flat, giving the weapon an unusual silhouette.

A skeletonized barrel jacket gave the necessary support for recoil of the moving parts and also served as a base for the front sight. Large flanges on the upper part of the barrel body acted as guides, while a flash hider was attached to the muzzle end. A graduated rear sight was placed on the receiver. It could be either elevated or depressed without need for the gunner to rise from the prone position generally taken when this weapon was fired. A large oil reservoir was built into the top of the receiver, directly over the

Breda Machine Gun, Model 1924, 6.5 mm.
The Operator is Loading the Weapon.

feedway. This lubricator was operated by the recoil and counterrecoil movement of the barrel and barrel extension, squirting oil with each complete cycle on the rounds then being positioned on the floor of the feedway.

To operate the Breda 1924 light machine gun, the gunner is generally in a prone position with the stock at his shoulder. The magazine is first released by its latch holder and the end pivoted towards the muzzle. This exposes the rear of the magazine so that the cardboard container holding 20 rounds of ammunition is positioned in the mouth and by a forward movement of the finger the cartridges are shoved into the magazine until the last round has been secured behind the holding pawl. At this time the cartridge container is discarded and the loaded magazine is swung into position with the last cartridge in place to be picked up by the bolt.

The charging handle is grasped by the right hand and pulled all the way to the rear, compressing the driving spring and cocking the piece. At the rearmost position the charging handle is released and it and the operating parts are all driven forward by the energy of the driving spring. On the forward travel of the bolt a feed rib on the side contacts the base of the first round in the magazine, forcing it towards the chamber. For approximately one-half the length of the magazine the cartridge slides forward held by the lips. When the round is slightly over halfway out of the magazine, under pressure of the spring-loaded follower it is kicked out of the feed system into alignment with the chamber. During this movement the nose of the bullet is guided by the bullet ramp on the bolt lock. Continued travel forward chambers the round, and the extractor snaps over into the cannelure of the cartridge case.

When the bolt is 1½ inches from home, it begins to enter the locking ring, and at a point 3/8 inch from its battery position, the bolt strikes the breech end of the barrel. The force of the strong driving spring causes the bolt, barrel, and

Components of the Breda Machine Gun, Model 1924.

lock to move forward. This motion causes the rear lug on the locking ring to engage the fixed cams in the receiver forcing the lock to rotate partially around the end of the barrel and the locking lugs on the front of the bolt, thus locking these two pieces positively into position. The Breda is now ready to fire.

Pressure on the trigger forces the sear release forward compressing its spring. The sear is cammed down out of engagement with the notch in the rear end of the firing pin which flies ahead to strike the primer detonating the powder. As the pressure from the explosion starts to build up, the locked barrel and bolt move together 3/8 inch to the rear. During this recoil the front lug on top of the locking ring engages the fixed unlocking cam in the receiver, causing the lock to rotate. The bolt is suddenly unlocked without benefit of initial extraction.

The extractor snatches the empty cartridge case from the chamber and holds it on the bolt face. The ejector riding on the right side of the bolt pivots out under tension of its spring. The extractor holds the case firmly against the ejector until it is snapped out when the ejection slot in the left side of the receiver is reached. As the bolt continues on to strike the buffer it also carries with it the firing pin. The rear end of the pin passes through the buffer into the sear housing. At this point the firing pin spring is fully compressed and the sear drops in its recess, holding it back under full tension.

On counterrecoil the bolt and all other operating parts are driven forward by the energy of the driving spring and the rebound of the recoiling parts off the buffer. As the bolt passes the magazine, it picks up a round and chambers it. When securely locked, if the trigger is still pulled back, the rear end of the bolt cams the firing pin safety sear out of the path of the pin, allowing it to go forward and fire the gun again.

On counterrecoil the bolt and all other op-other function. The oiler piston is cammed up into the oil cylinder by the bolt. As the piston is raised, it creates a pressure, squirting the lubricant out of a small spout on the right side of the cover. The latter is fixed directly in line with the mouth of the magazine so that incoming rounds are oiled as they are positioned in the feedway. On the recoil movement of the bolt, the piston rides in a groove on top of the bolt until it is approximately one inch from its rearmost position, at which time it has reached the end of its beveled cam. All pressure is released, and air taken in for the return stroke.

When the safety is placed on S, a guard shaped like the letter U is dropped over the trigger to prevent rotation. When changed to F, this part is removed and the trigger is free to move. As this weapon fired from a front-seared bolt and held

Breda Machine Gun, 6.5 mm, Showing Ease of Barrel Change.

a cartridge in the hot chamber after a long burst, a rear sear device was placed on this gun that allowed the gunner to pull the charging handle to the rear and hold the operating mechanism until cool enough to resume firing. To release this arrangement, the bolt handle had only to be retracted beyond its catch point.

The Breda Co. soon after the introduction of the 1924 model made several external refinements and brought it out in competition to the Fiat owned Safat plant which was at the time producing a machine gun that also carried the same designation and was known as Model 1926. The two guns were tested together and the Breda proved the best, although neither was adopted at the time. The Breda firm, however, was given an order for 2,000 not only to pay for time and effort spent in producing this gun but also to encourage continued development. Feeling that this sizable order warranted further improvements the designers 2 years later made a few minor changes in the appearance of the gun and gave it the official nomenclature of Breda Model 1928. The operating mechanism was, however, practically identical with the earlier models.

The firm also began production of a 12.7-mm aircraft machine gun in 1928 but did not get beyond a working model. Following unsuccessful trials on its own test range, the company abandoned the project.

Late in 1930 the Breda Co. took over from the Fiat Co. all machinery, patents, etc., for the manufacture of small arms such as machine guns and automatic rifles. Plans were made for the construction of a plant, called Breda-Fiat located at Piacenza, Italy, near the Fiat tractor factory.

The next venture was the 1930 model light machine gun made in 6.5, 7, and 7.92 millimeter bores. While given different model designations the mechanisms and methods of operation were identical with the 1924 model except for minor refinements and an assortment of calibers. This weapon was sold to other countries, Portugal and some of the Baltic states buying the 7.92 model. Development continued until the appearance of the 13.2-mm 1931 model gas-operated machine gun designed for antiaircraft and tank use.

The 1931 model Breda was a radical departure from previous designs. Early firing tests proved it to be basically sound. During the following years efforts were begun to scale the large caliber gun down to use the 8-mm cartridge.

This attempt culminated in the Breda model 1937. The gas-operated weapons of this type had many peculiar features. One of the most outstanding was the placing of the empty cartridge case back in the feed tray after firing and ejection of the whole tray. The breech lock was cammed straight up into its recess by action of the inclined surfaces on the piston extension, so that the projection on its upper surface engaged in an opening in the top of the body. The

Breda Machine Gun, Model 1930, 6.5 mm.

Breda Machine Gun, Model 1931, 13.2 mm.

cartridges were fed from plate chargers holding 20 rounds, each round being housed in a separate compartment.

No provision was made for single-shot operation. When the safety was removed, the weapon would fire full automatic only. A special clamp permitted quick barrel change, and the piston was made with an interchangeable head. Cyclic rate could be controlled by ten different settings of the gas regulator.

Like all Italian machine guns oil was used freely on the ammunition since head space was not adjustable on the weapon. The fixed relation between the front face of the breech-lock receiver and the gas port in the barrel made impossible rotation of the barrel in order to advance or retract the chamber for correct head space. The oiling of the ammunition was resorted to in this case in order to compensate for the above condition.

The firing mechanism was held in the cocked position by a rear searing device. When the pressure had been removed from the trigger button, the device dropped in position at the full-recoil stroke of the gas piston holding the entire assembly aft. The barrel was of unusually heavy construction (9 7/8 pounds) permitting the discharge of quite a long burst before overheating caused bullets to "tumble," with resultant loss of accuracy and effectiveness.

To fire the Breda Model '37, the operator inserts a loaded tray holding 20 cartridges in the feed slots in the left side of the receiver and the charging handle on the right side is pulled back as far as it will go. A searing device engages the gas piston locking the whole firing mechanism in the cocked position. When the operating parts are moved rearward by pulling back on the retracting handle, the feed tray is indexed over one space positioning a round. If the trigger is taken off safe position and the button pushed in, the sear is disengaged from the gas piston and the

Breda Machine Gun, Model 1937, 8 mm.

Breda Machine Gun, Model 1938, 8 mm.

assembly goes forward, pushing the cartridge out of its container in the feed tray into the chamber. When this is accomplished, the bolt stops and the gas piston continues forward, forcing the breech lock up into the locking recess in the top of the receiver. On the last movement forward of the gas piston after the mechanism is locked, a projection on top of the gas piston strikes the firing pin which in turn hits the primer to detonate the propellant charge.

The expanding gases forcing the bullet out of the bore enter a gas port on the underside of the barrel at a point two-thirds of the distance from the breech end. The gas upon entering the gas cylinder exerts a sudden pressure on the face of the piston housed by the cylinder. The impact force drives the piston to the rear. The piston movement pulls the firing pin back and the breech lock down, freeing the bolt. Its first stage of unlocking jacks the bolt back a few thousandths of an inch, loosening the empty case before fully unlocking.

The bolt and piston then start rearward with the extractor holding the cartridge case to the face of the bolt. At a point directly under the feed tray, a dog on the receiver stops the rearward motion of the case; at the same time a cam forces the empty case up into the space it formerly occupied in the feed tray. Continued recoil of the bolt and gas piston causes the next round to be indexed by a movement to the right of the ammunition clip. When all 20 rounds have been fired, the clip containing the empty cartridges is thrown clear of the gun on the right side after the last shot is fired.

The bolt and piston after striking the spring-loaded buffer start into counterrecoil and, if the trigger button remains depressed, the mechanism will continue forward to fire the next round.

This model of the Breda, chambered for the

Components of the Breda Machine Gun, Model 1938, 8 mm.

rifle caliber cartridge, showed only the weak points of an otherwise well-designed automatic firing mechanism and these features were corrected at once. It was felt the system of feeding was unsatisfactory; and the following year the 1938 model, having an overhead clip feed, was introduced. It ejected the cartridges out of the bottom of the receiver. The weapon also had a pistol grip. The operating parts and all other principles remained identical with the two preceding models.

A short while before the first of the gas-operated ground machine guns made its appearance, production of all automatic: weapons was put under the direct control of the government and Breda was given the assignment of developing an adequate aircraft machine gun. By the middle thirties Safat, the arms division still under control of Fiat, had made a few successful working models that employed the breech lock patented by Mascarucci. The mechanism was later improved by Breda engineers, who inverted the lock, putting it on the bottom, and added a muzzle booster and a recoil-actuated accelerator. These completed modifications were looked upon so favorably by the Ministry of Air that it ordered the immediate production of the gun. To expedite what was considered a superior aircraft weapon, after considering Safat's prior arms commitments, the government directed the Breda Co. to start making the weapon from drawings furnished by the originating company.

These guns were then designated Breda-Safat, Model 1935, to include both designer and manufacturer. They were made in three bores: 7.7, using the same cartridge as the Vickers and Lewis guns, 7.92, and 13.02, for use against armored aircraft and vehicles. The last cartridge was to have had an explosive bullet but it was found to be a violation of international law.

The 7.7-mm aircraft machine gun weighed only 27 pounds with a rate of fire of 800 rounds

Breda Aircraft Machine Gun, 12.7 mm.

a minute. Feeding was done by means of a metal disintegrating belt and was interchangeable from one side to the other. An extractor claw withdrew the loaded round and knocked out the empty case through the ejection slot in the bottom of the receiver. Charging was accomplished by means of a T-shaped handle fastened on the right side of the receiver. There was no provision for single shots. When the trigger was actuated, automatic fire resulted as long as it was held back. If mounted on a flexible gun, a pistol-grip handle with trigger guard was used. An arrow-shaped safety device was placed on top of the receiver, just behind the feed opening. British ammunition, caliber .303, would function satisfactorily in this gun. The chamber was fluted to facilitate extraction by allowing the high-pressure gas at the instant of firing to cushion or float the empty case.

When mounted as a fixed gun in a wing, a hydraulic charger was added. The weapon was carried in a cocked bolt position, allowing cool air to circulate through the bore after a burst. The muzzle booster allowed the expanding gas after the bullet had cleared the muzzle to be brought to bear on the face of the barrel. Thrust was thus added to the recoiling parts and in so doing unlocking was hastened. All of these factors together resulted in a higher cyclic rate.

While there was very little similarity in appearance, this Breda-Safat gun was the direct outgrowth of the first Fiat mechanism using the Mascarucci locking principle. The cycle of operation remained basically the same but later was refined and modified by adding accessories until it resulted in the standard aircraft machine gun of the Italian air force, regardless of manufacturing designation.

Chapter 22
Furrer Machine Gun

Col. Adolf Furrer, when serving as director of the Swiss Government's small arms factory at Berne, Switzerland, applied for a patent in 1924 on a machine gun that was to affect the automatic weapons used by Swiss soldiers for years to come. And while it was produced in great quantities in calibers ranging in size from rifle to cannon, the basic operating features remained identical.

His first gun was known as the model 1925 Furrer and was a lightweight (18 pounds) air-cooled ground gun with a shoulder stock. It was clip fed by a 30-shot magazine, and chambered for the 7.5-mm infantry rifle cartridge used in the Swiss army for over 40 years. The barrel had longitudinal ribs to give strength and cut down dispersion, besides allowing more radiation surface for cooling purposes. It was constructed of steel that had been given a special heat treat to insure greater life. These barrels were manufactured by Rudolf Haemmerli of Lenzsburg, Switzerland, who also made a number of the weapons under contract.

Colonel Sonderegger, then Chief of Staff of the Swiss Army, was impressed by the performance of the simple mechanism of Colonel Furrer's design and ordered its manufacture on a limited scale until fully corrected by firing and endurance tests. By 1928, however, 5,150 weapons of the 1925 model had been made and delivered to the army. The French, being skeptical of Swiss claims that the barrel could fire 25,000 rounds and retain a semblance of accuracy, bought one gun, several barrels and enough ammunition to test it. They reported that the barrels could fire as much as 18,000 rounds "without appreciable loss in accuracy of fire."

The normal rate of automatic fire for the ground gun was 450 rounds a minute maximum. Every gun was furnished with 34 spare magazines holding 30 rounds each. It was necessary to stop and allow the barrel to cool after 400 shots had been fired full automatic. A device working in conjunction with the safety permitted the operator to fire single shot or full automatic as desired. It was recommended that the gunner fire the weapon in bursts of six or eight shots until the magazine was empty.

The 1925 model was closely followed by a 13-mm version, having a rate of fire of 300 rounds a minute with a muzzle velocity of 2,624 feet a second. This gun weighed 66 pounds and was adaptable to both antitank and aircraft. One of the most novel features in the construction of the Furrer weapon was that the barrel was changed by pulling it, with the entire firing mechanism remaining attached, from the rear of the receiver. A new firing mechanism and barrel assembly were then inserted. This complete change of both operational parts and barrel was quite unique in machine gun design.

Furrer made skillful use of timing his weapon, which was so constructed that the barrel and its extension were held in a retracted position after unlocking. When counter recoil was approaching the end of its stroke, with the barrel and bolt securely locked, the gun fired a few thousandths of a second before the fast moving parts collided with the stationary receiver. This allowed recoil to start before metal-to-metal contact was achieved, giving the weapon a unique buffing action that produced not only smooth performance but added greatly to the longevity of its components.

The locking and unlocking of this mechanism was accomplished through the breaking of a toggle joint by a hinged lever in the rear that was fastened by a pin to the receiver. When the toggle was broken, the locking lugs began to be released and roll about a curved surface until they were completely disengaged. All models had a very strong buffer and driving spring. A flash hider, blast suppressor, and muzzle booster were always incorporated in the construction.

Furrer Machine Gun and Components, Model 1925, 7.5 mm.

For aircraft use the metal non-disintegrating belt was employed. The fixed guns were made to be interchangeable with flexible ones. However, mounting as free guns was always done in pairs with ammunition boxes holding 120 rounds each feeding from above so that ejection would be down into the fuselage or into an empty cartridge-case container.

The Furrer guns were highly characteristic of the Swiss genius for precision-made instruments and equipment. The weapons were made up of a multiplicity of intricate parts that performed unusually well but did not lend themselves to mass production.

The aircraft models had the following interesting details in common: (1) Feeds that were interchangeable from left to right, or vice-versa; (2) mounting of guns for either flexible or fixed use; (3) a rounds counter on the back plate showing the gunner, when firing flexibly, how many rounds were left in the ammunition box; (4) a feed pawl disengagement which halted feeding in order to leave the bolt in battery on an empty chamber when overheated; (5) a belt that did not disintegrate when a round was withdrawn, being loaded with 120 rounds for flexible guns and 500 for fixed installations; (6) a short muzzle booster and bearing support; (7) longer barrels than those employed on the same mechanisms for ground use; and (8) a single grip on the flexible gun in lieu of the conventional two-grip, or spade, type.

The rate of fire of aircraft models using rifle-caliber ammunition was increased to 1,200 rounds a minute by the employment of a special apparatus. This device trapped the still-expanding gas after the bullet left the bore and brought it to bear on the muzzle of the barrel, causing the latter to be thrust suddenly to the rear. The added recoil hastened unlocking which, together with a strong spring-loaded buffer, gave an appreciable increase in cyclic rate. In fixed installations the gun could be mounted in practically any desired position as ammunition was fed in

on one side and ejected from the opposite one.

An example of the ingenuity of the Swiss armament designers is found in the national small arms factory at Berne, where the Furrer guns were produced. The nation realized that a war would make steel in large quantities practically unavailable and an emergency system whereby worn-out infantry rifle barrels could be used as reliners for machine gun barrels was developed at the Berne plant in the period prior to World War II.

The following method was used: A worn-out rifle barrel is heated in electric furnaces and drawn out to proper shape. It is then inserted in a deteriorated machine gun barrel which has previously been drilled out to proper diameter. The inserted barrel is then expanded by the auto-frettage method of forcing a series of reamers or wedges through the interior until it has been expanded to the desired dimensions. This cold-working produces a very hard metal and lengthens the life of the lined barrel. The insert is then drilled, reamed and rifled to correct specifications.

Otto Walker, an inventor of firearms and their accessories, residing in Zurich, is sometimes erroneously credited with originating what is known as the Furrer system. However, research does not show any basis for the claim. Colonel Furrer was the creator of the action named for him, despite its close resemblance to the Borchardt, or, as it is more commonly known, the Luger, action.

The cycle of operation on all Furrer-type automatic weapons is as follows: After the belt, or magazine, is put into place, bringing the cartridge in position to be picked up by the bolt face, the action is retracted all the way to the rear. When released, the compressed driving spring gives the firing mechanism a thrust forward. As the bolt face comes abreast of the rear of the feeding system, a loaded round is shoved forward into the chamber. On the last fraction of an inch of forward travel the toggle joint is forced into line and locks, cocking the piece. The weapon is now loaded, ready to fire.

The sear is rotatable in the breech-bolt frame, and upon being actuated, pivots, releasing the

Drawing of Furrer Machine Gun Action.

Furrer Machine Gun, Model 1925, 7.5 mm, Left Side.

firing pin to fly forward under tension of its spring and strike the primer of the cartridge. This in turn fires the charge. For the first fraction of an inch of recoil the barrel is rigidly connected with the barrel extension and bolt. During this time it slides backwards under action of recoil in the guides cut in the stationary receiver. The breech-bolt frame contains the bolt which is also moving rearward. It is connected by a link with the front end of a pivoted member also in the form of a link.

The latter is rotatably mounted in the breech-bolt frame on a pivot. The rear end is connected by means of a pivot pin with one of the supporting links, the other end of which attaches to the barrel extension. The bolt only becomes unlocked from the barrel after the barrel and breech bolt have reached a point where a projection in the stationary receiver breaks the straight-line action of the pivoting links. This allows the bolt to open slowly at first to produce initial extraction and then to complete the function, carrying the fully loosened cartridge case held to its face by the extractor.

The first breaking action of the links withdraws the firing pin slightly within the bolt face. The continued recoil movement not only holds the firing pin in this position but carries the cartridge to a point where its base collides with an ejector that is built into the receiver. At this point the empty cartridge case is pivoted and ejected through a slot opposite the one through which it was fed. The barrel with its extension being unlocked from the bolt remains in a retracted position. The bolt having completed its full recoil stroke starts counterrecoil movement and the bolt face, when in position, picks up the incoming round out of the feedway ready for chambering.

At this time the projection on the firing pin catches the sear mounted in the barrel extension. In the final act of locking, the bolt compresses the firing-pin spring. When the bolt and barrel are locked, the continued thrust of the driving spring then shoves the retracted barrel assembly into battery. If the trigger remains depressed, the sear releases again, firing the chambered cartridge.

The Furrer is so constructed that the firing pin can be released before the locked bolt and barrel strike the receiver, and in this manner the fast-moving counterrecoiling parts are buffed with the start of recoil before making metal-to-metal contact.

Chapter 23
ZB Machine Guns

ZB Model 1926

The arms producing company, Ceskoslovenska Zbrojovka Akciova Spolecnost v Brne of Brunn, Czechoslovakia, was first formed in 1922. It began as a stock company, with 75 percent of the shares owned by the government, 20 percent by the Skoda Works and 5 percent by the employees. In its early days it manufactured not only automatic weapons but also military rifles and two-cylinder automobiles.

The first machine gun from the new company was the light Hotchkiss model of 1922, built through the cooperation of French authorities. Relations between the war offices of France and the Czech Republic were extremely close and the manufacture and sale of automatic arms by the new state were encouraged by the French.

In 1924 the firm introduced a prototype weapon of its own design, identifying it by the year of its first appearance. This weapon was less an invention than a devisement, being an application of many sound automatic weapon principles that had been proved by use in other guns such as the Berthier, B.A.R., Hotchkiss, and Chatellerault. Development continued until it was thought to be perfected to a point where it could meet all demands placed upon it. It became known as the Brno ZB Model 1926, the initials obviously coming from an attempt to reach an intelligent solution to a name foreigners found impossible to pronounce, with Brno being an earlier spelling of Brunn.

Of the many skilled gun designers who contributed to the various models of ZB machine guns, perhaps the most outstanding were the Holek brothers, Vaclav and Emanuel. Both were natives of Czechoslovakia. Other well known designers in the employ of the firm were Anton Marek, an Austrian by birth, and Antonin Podrabsky, a Pole.

Vaclav Holek stood head and shoulders above the rest of these capable men. Starting as an ordinary workman in the Zbrojovka works he showed great interest in machine gun design and produced several working models of his own while still a foreman gunsmith. A demand for a light machine gun by the Czech Army soon after the nation gained her independence gave him the opportunity for which he had been waiting,

ZB Machine Gun, Model 1925, 7.92 mm.

and he designed the first of the series of ZB light machine guns. Completion of this model took him only three years from conception to finished product.

At the time he was only being paid the equivalent of $20 a week, but he patented various features in the devisement of the weapon that later not only made him a very wealthy man but saw him quickly promoted to chief of the plant's experimental laboratory. The Czech Army officials put the company's first offering through the most strenuous tests they could conceive. During the trials the rugged mechanism stood up even after being buried in mud or fired until the barrel was red hot and then dropped purposely in a vat of cold water.

The Brno Model 1926 comprised 143 component parts in two categories, fixed and recoiling. To the former belonged the barrel, receiver, trigger mechanism, stock, and magazine. The recoiling parts were the bolt, bolt carrier, gas piston, and driving spring.

The barrel on the model adopted by the Czech Government was chambered for the 7.92-mm infantry rifle cartridge. Its outer surface was covered with cooling fins. On the breech end there were interrupted threads divided into three sections which permitted solid locking to the receiver by means of a locking nut. On the under side of the barrel was located the port, through which the expanding powder gases were directed into the gas cylinder housing the piston. A lug in the receiver was fitted into a slot below the chamber. When locked, it prevented the rotation of the barrel but it forced longitudinal movement forward when loosened. The middle of the barrel had a removable collar to which the carrying handle was attached. If turned to the left, the handle could be grasped by the gunner when firing to stabilize the piece.

The inside of the receiver was milled out square to contain the operating parts. On the forward end was an extension to which the gas cylinder was screwed. The upper part formed the barrel bearing in which the locking nut was bedded in such a manner that it could rotate but could not be displaced. The nut had a tap divided into three sections corresponding to the thread on the barrel and possessed an arm by which, in its vertical position, the barrel

Section Drawing of the ZB Machine Gun.

coupling was closed and retained on the receiver by a spring-loaded pawl. When the arm was turned at an angle of 60 degrees, the pawl, acting first on the lever, caused a separation of the barrel and nut, at the same time making the former move forward. It then was easily removable by a pull on the carrying handle.

The extension of the receiver was joined in front to the gas cylinder that extended under, and parallel to, the barrel. This part housed the gas piston, while the top of the receiver had a rectangular opening into which the loaded magazine was inserted by a single operation of the hand. On the rear edge of the opening were a spring-loaded pawl and the fixed ejector. The bottom had an opening through which the empty cartridges were ejected. The opening had a sliding cover which was moved aside at the first firing.

On the right side was the cocking handle. The slideway in the receiver contained a strong spring clip that held the handle in forward position when it was returned after firing the first shot. At the rear and partly below, the stock was joined by two hinged bolts. It contained the driving spring and trigger guard, through which, after the upper hinge was loosened, all the operating parts could be pulled out from the rear of the receiver. This greatly facilitated examination, maintenance, or repair in the field.

The magazine was a simple sheet-metal box into which two rows of 20 cartridges each were staggered. They always were held against the receiver wall because of pressure from above by the compressed magazine spring.

In the gas cylinder the piston moved on its extension in the bolt carrier housed in its slide-way in the receiver. A lug on the bolt carrier, opposite the firing pin in the bolt body, formed the hammer. On the under side of the bolt carrier was a recess into which the sear of the trigger mechanism was engaged. The bolt carrier was the driving part of the bolt and transmitted to this part forced movements back and forth. Locking was caused by two beveled lugs on the bolt carrier engaging two other lugs on the bolt. The lifting into the locking recess was accomplished by the carrier camming these parts up with its locking lugs, the bolt rising on a bearing against the fixed receiver during the instant of discharge and remaining until the bullet was out of the bore.

A device that permitted the firing of single shots if desired was called the interrupter. When the safety was turned for single-shot firing, the interrupter was pressed down during firing by the recoiling bolt carrier. Thereby the sear was liberated from its locked position and engaged the notches in the bolt carrier after the firing of each individual shot, necessitating the pulling of the trigger each time to fire a shot. If the safety were put on automatic firing and the trigger kept to the rear, the sear remained in a down position and would not catch the shuttling bolt and bolt carrier.

The striking of the firing pin by the bolt carrier was accomplished by a system known as

ZB Machine Gun, Model 1926, 7.92 mm.

inertia firing. When the last cartridge had been fired out of the magazine, the bolt and its carrier were held in a cocked position by the feeder plate protruding from the magazine mouth. At the insertion of a loaded magazine, the bolt and carrier moved forward a few thousandths of an inch to be blocked again by the sear. This allowed the bolt to be held ready to fire at the moment the magazine was placed in position.

This light Brno ZB Model 1926 possessed the technical qualifications necessary to satisfy all tactical conditions under which it would be used. The factory was well equipped with the most up-to-date machine tools. Operations were organized on modern principles of mass production so that all machine gun parts made in the factory were interchangeable. The steel used was provided by the world-famous Skoda plant.

The normal effective range of the gun was said to be 1,000 to 1,200 yards. Location of the magazine on top meant that the sights had to be offset to the left. The maximum cyclic rate was 450 to 500 rounds a minute. Each gun came equipped with two barrels and to change them was but a matter of a few seconds. The red-hot barrel could be plunged into cold water without any ill effects. If fire was maintained at a rapid rate, it was recommended that the barrel be changed after every third magazine had been emptied.

The Bren Gun

In 1932 the British Army, in its quest for a light machine gun to replace the Lewis, became very much interested in its military attachés' reports on the simply constructed reliable machine gun known on the Continent as the ZB Model 1926. A series of trials were immediately begun in which by way of competition some fine and efficient weapons were entered. Among them were the well-known Madsen and Vickers-Berthier. The latter seemed certain to be adopted, but after an exhaustive test the British decided on the ZB weapon. Certain changes were demanded in order to meet British ammunition characteristics. The specifications were drawn and submitted to the parent company. The result bore the temporary designation of Model ZBG.

Two principal changes from the earlier models were made. The removable barrel was chambered for the caliber .303 infantry rifle. It was shortened and the gas port was brought nearer the breech end to compensate for the shorter barrel. The stock was also modified and a recuperator spring added in the recoil mechanism to permit a slight barrel movement rearward. These modifications gave a higher rate of fire and a considerably smoother action. The stock did not hinge, due to a redesign of the recoil mechanism.

In February 1934 the London Telegraph carried an article by Capt. B. H. Liddell Hart, from which the following is quoted:

"A start is to be made this year in equipping the British army at home with a new light machine gun. The cavalry are to be the recipients of the much needed replacement of the obsolescent wartime weapons still in use. The new weapon is known as the ZB, a new light machine gun of Czech origin, which has come to the front as a 'dark horse' in recent tests. . . ."

Having obtained a license to manufacture it, the Enfield government arms plant was ordered to begin manufacture of the weapon and in January 1935 the completed drawings from the ZB firm were received. In September 1937 the first gun was assembled and given the name Bren, the first two letters being taken from Brunn, location of the original producer in Czechoslovakia, and the last two from Enfield, the British arsenal. By December 1937, 30 Bren guns had been completed, with 12 already under test. By January 1938 an even 200 guns had been assembled. By July of the same year production had been stepped up to 300 a week and remained at that figure until September 1939, when it was found that the guns were coming off the assembly line at a rate of 400 a week.

The Royal Small Arms factory continued to be the sole producer of the weapon, with B.S.A. and Austin having contracts for the production of spare magazines. The feed systems made by the latter two companies gave considerable trouble because the Czechs designed the magazines to hold rimless cartridges, while the British continued to use outmoded rimmed ammunition for their automatic weapons. The mistake was remedied but not before thousands of magazines

Bren Machine Gun, Mk I, Cal. .303.

had been manufactured. It was found that they would function correctly if loaded with only 29, instead of the customary 30, cartridges. The magazines were marked plainly to this effect. Issued after the outbreak of World War II, the weapon was manufactured in tremendous quantities not only in England but in Canada as well.

Japanese Models of the ZB

In the year 1936 a ZB-type gun made its appearance in the Japanese Army and was designated Model '96, 6.5-mm. Research shows that the weapon actually was produced in a Chinese arsenal which, when captured by the Japs, continued operation and placed many such arms into the hands of the Japanese infantry. The gun was later adopted and produced in Japan, becoming a part of the country's haphazard automatic armament. It appeared as Model '97 (1937) for use in tanks, and as Model '99 (1939), with a lighter construction for infantry and paratrooper use. Both were chambered for the 7.7-mm cartridge.

Some of the tank models were designed to mount a long telescopic sight on top of the

Bren Machine Gun, 7.92 mm. A Czech Weapon Adopted by the British and Manufactured for the Chinese in Canada.

ZB Machine Gun, Model 96, 6.5 mm.
A Japanese Copy of the Czech Weapon.

receiver. A manual captured with one of the guns shows that the weapons were identical with ZB machine guns used practically all over the world. A translated portion of the manual is given below:

"The Japanese Model 97, 7.7 tank machine gun is a gas-operated air-cooled Brno-type machine gun designed to be mounted in tanks. It is equipped with conventional sights and also has a telescopic tank-type sight mounted on the left side of the receiver. The use of conventional sights and a bipod carried separately in the tank allows the gun to be used on the ground as well as in the tank. The weapon has a removable box magazine holding 30 rounds and uses only the Model 99 rimless 7.7 ammunition."

Unlike the original ZB machine guns there was no carrying handle on this particular model and the cooling fins ended 5½ inches from the muzzle end of the barrel. The operating parts were as identical as it was possible for the Chinese and Japs to copy.

ZB-50 Machine Gun

The ZB Co., after a number of years' experience with its light gas-operated machine gun that enjoyed a world-wide reputation for reliability and clean cut design, turned its attention in 1932 to the promotion of a machine gun that operated by recoil forces. In the creation of this new weapon the company advertised that it "made efficient use of all the knowledge and methods which modern technical science puts at the disposal of the successful designer. Painstaking study and research were undertaken to determine kinetic and dynamic conditions in the mechanism of the machine gun. Cinematopographic research was made use of, and radiation of heat from the barrel was the subject of thorough investigation based on the latest data of the science of thermology."

This weapon was given the official designation of ZB-50 and the main change was that the breech mechanism was operated by utilizing the recoil, and the bolt was cushioned by a strong spring so that this heretofore undesirable feature did not influence the accuracy of the weapon when in the act of firing.

The bolt assembly was very similar in appearance to the earlier gas-operated models, but in lieu of a gas piston actuating the recoiling parts an accelerator was added that transferred energy

ZB Machine Gun, Model 50-1932, 7.92 mm.
The Only Weapon Designed by ZB Based on the Short Recoil Principle.

during the movement of recoil and at the instant of unlocking exerted its full force on the bolt, speeding it rearward. These features were invented and patented by Anton Marek, one of the noted gun designers in the employ of the ZB plant. The accelerator was in appearance very similar to the well-known Browning type.

This model unlike its magazine-fed predecessors employed metal push-out type links to form a non-disintegrating belt for the purpose of placing cartridges in the feedway. After the discharge of the last round the belt fell out the left side and the bolt and its components were held by a stop in the cocked position. When a loaded belt was inserted, the stops were raised and the bolt moved forward a few thousandths of an inch to be caught by the rear sear. This necessitated a pull of the trigger to release.

The only thing needed for complete disassembly in the field was a loaded cartridge, with the bullet point being used to depress certain spring-loaded detents.

The trigger housing was so designed that it slid on the bottom of the breech casing when released from its spring-loaded detents to cock the mechanism manually. The housing had two small grips on each side that acted as the charging piece. The advantage of this arrangement was that the two grips could be used to cock the piece when it became necessary to load the weapon by hand.

A muzzle booster that trapped the powder gas after the bullet left the barrel was used to increase rate of fire by bringing this pressure to bear on the face of the barrel. This device working in conjunction with the mechanical accelerator gave a cyclic rate of 600 shots a minute. The muzzle booster was also designed so as to act as a Hash hider and front barrel bearing.

The safety catch was of unusual design on this weapon, being so constructed that, when it was on, it held not only the sear locked but also threw the point of the incoming round down at an angle so that if by any chance whatsoever the sear did become disengaged and the bolt go forward the cartridge was in such a position that it would not chamber.

Perfect coordination between the counterrecoiling barrel and the moving belt was assured by a specially constructed piece that permitted the return movement of the bolt only after the barrel had gotten into battery.

To fire the ZB-50, the gunner, generally prone, raises a cover in front of the feedway and inserts a loaded cartridge belt from the right side until the first cartridge is under the spring-loaded holding pawl. Then the firing grips are released from their detent and shoved forward until the sear engages the bolt. It is then pulled all the way to the rear. At this point the rear sear engages its recess in back of the bolt, holding the firing mechanism in the retracted position. Rearward motion also compresses the driving spring

and moves the belt over one space in the feed-way, thus positioning the first round. When the trigger button is pushed, the sear disengages the bolt which flies forward under the influence of the driving spring energy.

The bolt face, arriving at the rear of the feed, begins the first phase of chambering the round by pushing it out of the link into the guideway that positions the nose of the bullet into the entrance of the chamber. The bolt is made in two pieces. The portion containing the bolt and its rear locking face arrives in battery first with the rear end directly under a locking recess milled into the barrel extension. The second part, which is connected to an extension spring and is held to the rear of the first part by means of the locking lug, is now free to move forward. The angle on the locking lug cams the back end of the bolt up into the locked position. The last forward motion of the bolt assembly's second portion brings the face of the locking lug to bear suddenly on the firing pin housed in the bolt and the weapon is fired.

In the first half inch of recoil, the bolt assembly and barrel are locked to the barrel extension. At the same time they build up tension in the extension-type mainspring. This spring is connected to the accelerator which, upon being activated by the spring, pivots and shoves to the rear the part of the bolt carrying the lug. This unlocks the weapon and also accelerates the already recoiling parts to the rear. The empty case is withdrawn from the chamber and ejected through the bottom of the receiver. When the bolt assembly reaches its rearmost position, counter recoil will begin, repeating the cycle of operation as long as the trigger button is depressed.

Besa-ZB-53 Machine Guns

The British modifications on the 1926-30 models that became known as the Bren led the ZB firm to bring out an identical gun in every respect except for the caliber. This was changed from the British .303 to the Czech rifle cartridge, 7.92 millimeter. The greatly improved design was called the ZB Model 1934 and the highly efficient weapon was bought or copied by countries all over the world.

In 1937 V. Holek, the official in charge of the firm's experimental weapon design, introduced and patented a gas-operated firing mechanism that was given the official designation ZB-53 Model 1937. While it had many physical changes, the operating parts remained basically the same as all the other gas-piston-actuated ZB's.

The British were much impressed with this weapon and adopted it at once for equipping their armored vehicles. They proceeded to acquire manufacturing rights, and in a short time it was being produced in England in the Enfield Royal Arms Manufacturing Arsenal and the Birmingham Small Arms plant. This gun produced in England was known as the Besa. ("B" for Brno, "E" for Enfield, and "SA" representing the last two initials of the Birmingham firm.)

British cartridges not being suitable for the action, the barrels were chambered for the 7.92-mm Czech cartridge instead of their own caliber .303.

ZB Machine Gun Model 53-1937, 7.92 mm.

Later the same mechanism was scaled up by the ZB Co. to take a 15-mm high-velocity cartridge for anti-tank use. This large bore machine gun was likewise adopted and manufactured by the British. The smaller caliber guns were designated Besa 7.92-mm Mk I and II; the larger weapon was known as the Besa 15-mm Mk I.

The physical appearance of the guns themselves was rather conventional, but a few features most certainly were not. The charging handle for cocking the weapon was the pistol-grip-shaped trigger guard that was shoved forward until a sear engaged the piston extension. The guard was pulled back, carrying the operating parts to the rear sear, after which it was returned to its normal position. Needless to say, the fingers must not be placed inside the guard as pulling back into place would fire the weapon after return of the guard to its former position.

Before the barrel could be removed, the gun must always be cocked. Two different sized orifices were drilled into a circular piece that could be rotated. This was inserted between the port in the barrel and the gas piston cylinder. By turning this part, the gunner could obtain an adequate amount of gas for successful operation.

The Besa--ZB-53 guns were equipped with considerably heavier barrels than most air-cooled machine guns. Bursts of greater duration were thus made possible. They also differed from the earlier ZB-model guns from which they originated in that they had no shoulder stocks and that the rear of the receiver housed a heavy spring-loaded buffer system that could be set to deliver a slow or fast rate of fire. This device could be moved up out of the way. Then the bolt could not only travel farther on the recoil stroke but had the energy of the compressed driving spring alone to return it. This noticeably slowed the action and, when used with the small orifice, produced a rate of fire of 450 to 500 rounds a minute. If a higher rate was desired the operator snapped the L-shaped heavy buffer in the down position. The stroke was then shortened and the fast recoiling bolt was deflected back to battery at a higher speed. The use of this buffer, often erroneously called the accelerator, gave a rate of fire of 800 to 850 shots a minute.

The principal difference between the rifle-caliber weapon and the 15-mm Besa were the features in the latter that were patented by V. Holek, namely the method for holding the barrel to the rear by a spring-loaded detent. The bolt had to chamber the cartridge slightly out of battery and the firing take place before the fast moving components made metal-to-metal contact on counter-recoil. This allowed the recoil forces to begin just before the stopping of the bolt, barrel, and extension by the receiver. This not only gave longer life to the operating parts but resulted in smoother functioning.

The method used in retracting the barrel was unique in that the cover had to be raised. This actuated a linkage that jacked the barrel back until the detent located on the bottom side slid into its recess. Cocking was done also by the unusual method of releasing the pistol-grip-shaped trigger guard. It was shoved forward until it latched on to the rear end of the gas piston and was then pulled to the rear until the sear engaged it to hold in until released by the trigger. A continued movement rearward naturally

Besa Machine Gun, Mk II, 7.92 mm.

brings the trigger guard back to its normal position.

The so-called accelerator was not incorporated in the design of the larger caliber weapon. The device was in reality a strong spring buffer that could be dropped into position to shorten the recoil stroke and speed up by bolt deflection the rate of fire. The barrel was machined in such a manner as to have three points of contact with the inside of the barrel jacket. This gave sufficient support but did not create undue friction on recoil.

By turning the selector switch to its extreme left position, single shot firing could be accomplished. The feed system used the metal push-out type of link and was fed from right to left. The belt was drawn over one space by a lug on the gas piston which engaged the feed pawl and by a long movement gradually but forcefully pulled the belt over during each movement of recoil.

While the barrel could be readily removed, it was still a two-man job, for one had to hold it while the other raised the carrying handle of the barrel retainer a half inch and pushed the partly freed barrel forward until it could be turned up. At a distance of 13 inches from the breech end, a special slot was machined for this purpose. The second man then raised the aft end until it cleared the barrel extension. They jointly eased it forward to lift out. The projection guides on the barrel were freed from their slideways in the receiver by the last of the forward motion.

A flash hider was always used on this heavy duty gun as the terrific powder charge in the 15-mm cartridge had enough muzzle flash to impair seriously the aim of the operator unless suppressed by some device.

The cartridges were fed to the gun through a feed mechanism actuated by the piston extension. The latter piece was provided on its lower face with a cam way in which the under arm of the feed lever operated. The upper arm actuated the feed pawl and moved the belt over one space, positioning the cartridge to be chambered. The feed system was not dependent on the action of the breechblock but obtained its operational power from the piston extension. This method insured positive feed as the power stroke was used in place of energy derived from a compressed driving spring.

ZB Machine Gun, Model 60-1938, 15 mm.

Besa Machine Gun, Mk I, 15 mm, as Viewed from Below.

This weapon was so close in principles of operation as to be nearly identical with the early gas-operated ZB guns but the few new features added from time to time were in themselves radical enough to warrant the presentation of a cycle of operations for comparative purposes.

To fire the 15-mm Besa Mk I or the ZB-60 Model 1938, as the Czech company version was marked, the operator shoves the tab of the metal cartridge belt through the feedway from the right side, which is then pulled to the left until the first cartridge snaps behind the belt-holding pawl.

The detent holding the feed cover group is held down allowing the cover to be raised to the up position and then brought back to position. This movement jacks the barrel back where it is held in the retracted position by a strong spring-loaded catch. The pistol-grip trigger guard is released, allowing it to be slid forward in its slideway until a plunger in its housing is forced into a recess in the piston extension. The trigger-guard housing is then pulled smartly to the rear bringing with it the bolt and the extension.

At the completion of the rearward movement the rear sear engages the notch in the piston extension, holding the entire assembly in the cocked bolt position. The pistol grip that has served as the charging handle is now in place and, if the selector switch is on single shot or full automatic, the weapon is loaded and ready to fire.

The rearward movement of the piston extension also cammed the feed pawl over, thus positioning a round to be stripped from the link. The release of the sear by pulling the trigger starts the firing mechanism toward battery and a projection on top of the forward part of the bolt passes through the center of the link, shoving the cartridge ahead of it into the chamber. The bolt arrives first into battery with the rear end directly under its locking recess in the bolt extension. The gas-piston extension, being held to the rear by a beveled locking lug, can now continue forward since the lug cams the rear end of the bolt up into the recess and out of its path. The last fraction of an inch of travel of the piston extension releases the barrel holding catch and the entire assembly--bolt, barrel, piston, and extension--start final movement to battery. The faster moving locking lug on the piston extension, however, strikes the firing pin, discharging the weapon and starting recoil movement slightly before all the moving parts strike the stationary receiver.

The main recoiling parts are locked together until the terrifically high gas pressure has dropped to a safe operating limit. At a point in the barrel one-third of the way up from the breech, gas is let through a port into the chamber, where it strikes the face of the piston driving it rearward. The bolt is unlocked as the back of the lug on the piston extension pulls it down out of its recess. At the same time the retracted barrel is held back by its latch. A strong extractor withdraws the empty cartridge from the chamber and holds it until it strikes the ejector positioned in

Besa Machine Gun, Mk I, 15 mm, Top View.

the belt guide. It is then knocked downward through the slot in the piston extension and receiver.

Continued rearward movement completely compresses the driving spring and final travel of the recoiling parts is dampened by the heavy spring buffer. The barrel recoil spring positioned in the cover group reduces the upward jump of the barrel's muzzle and in doing so increases accuracy.

This weapon was intended for aircraft use as well as anti-tank work. For the former purpose an explosive 15-mm bullet was developed. Its high muzzle velocity of 3,200 feet a second was used as an argument in favor of its use in place of the larger bore automatic weapons then being placed in fighting planes. For ground work 40 rounds was the normal length of an ammunition belt, but the company was quick to point out that in aircraft installations the length would be governed only by the capacity of the plane.

The very modern and highly efficient ZB automatic arms plant was taken over by the Germans early in World War II and operated throughout the war under the name of Waffenwerke Brunn A. G. The conquerors not only used the excellent ZB weapons already in existence but kept production going in full force. Characteristically, they called for many modifications on the weapons, some in the nature of improvement and others merely for adaptation to special purposes.

The most outstanding illustration of the firm's craftsmanship, showing its genius for weapon design to the utmost, was an experimental model of a new type of machine gun that was in prototype stage at the time of the German invasion. Fortunately for the Allies, the model, pictures, and drawings found their way to the United States just before the plant fell into enemy hands. Security reasons do not permit any further mention of this weapon.

Chapter 24
Vickers-Berthier Machine Gun

In 1925, the Vickers Co. in England, having acquired the manufacturing rights to all Berthier machine guns, started production on a limited scale. This was done more to keep the personnel of its large Crayford plant employed than to fill the needs of the British services for a machine gun, since at this time the gun-making industry, as far as military types of automatic weapons were concerned, was at a low ebb.

The first such guns produced were in the form of light machine rifles. They were put on the market commercially, engaging in competitive tests in many of the Balkan States and in the 1 hitch East Indies. The Latvian military authorities adopted the light machine rifle chambered for their infantry rifle cartridge. In the Dutch East Indies test, the Vickers-made Berthier bested the field but no contract was received because the Dutch Government thought it more economical to manufacture a modified royalty-free Lewis gun in its own government arsenal. Spain bought a number of the weapons for use in Morocco and many South American republics purchased them in limited quantities. They were also adopted officially by the Indian Army. Actually the sum total of sales was only enough to keep this part of the Vickers Co. operating at a bare profit.

It was more from financial necessity than military need that Vickers in these days started to develop an aircraft gun based on the Berthier principles. An effort was made to interest the Royal Air Force in its adoption as an ideal observer's gun. The result is officially known as the

A Berthier Machine Gun, Cal. .30, Mounted as a Flexible Gun in a Curtiss Plane by the U.S. Navy, 1917.

Vickers G. O. ("gas-operated") machine gun, which made its first appearance in 1928.

Its main selling points were the extreme simplicity of its characteristic features and its very light recoil. The principal components could be assembled and disassembled without the aid of tools, and so constructed that they could not be put together incorrectly. The operating parts were housed in such a manner as to protect them from inclement weather. The silhouette was very clean, having no objectionable knobs or handles that would shuttle back and forth while firing.

The recoil was so light that a gunner could get in long bursts without being thrown off his aim. When overheated, the easily detachable barrel could be changed by an experienced operator in five seconds without touching it manually or disassembling other parts of the mechanism. The Vickers Co. recommended that a barrel be changed after a 240-round burst of rapid fire, but held it was possible to continue on if necessary. If it was determined that longer bursts were needed in aerial combat, a heavier barrel could be used and the ability to keep up sustained fire for great lengths of time could be greatly augmented.

All components were interchangeable, and manual manipulation of a device located near the trigger would instantly give the gunner a choice of single-shot or automatic fire.

The Vickers designers, knowing the main difficulties encountered in the maintenance of a machine gun in the air, tried to overcome these objectionable features by making it possible to change the extractor and ejector externally, if broken or damaged during fire, without stripping the gun. If disassembly for any reason was necessary, it could be done in less than 30 seconds. In order to take advantage of all cooling, the breech remained open upon cessation of fire leaving the hot chamber empty. This not only made a cook-off impossible but permitted cold air to circulate through the bore.

A drum-shaped feed of peculiar design, holding 97 rimmed caliber .303 cartridges and weighing 11 3/4 pounds when loaded, was used. This system, although resembling the Lewis feed in many respects, did not rotate when the weapon was firing, as it was latched securely in place fore and aft. Each round was positioned by means of a pre-tensioned spiral spring.

A very clever rounds counter was also incorporated in the G. O. gun's design. To wind the spring, a flat piece is located on top with a recess cut for inserting the finger. When the drum is fully loaded, this flat winding lever revolves and the gunner can see at a glance how many rounds remain in the drum. The top of the drum is marked in such a manner that, whenever the combination winding lever and rounds indicator stops, the amount of ammunition left in the feed is revealed.

The addition of accessories necessary for aircraft use was the only difference between the ground machine rifle and the observer's gun. In the latter, however, the rate of fire was stepped up to 950 rounds a minute by a larger gas orifice leading to the gas cylinder chamber and a more efficient heavy-duty buffer to compensate for the faster recoiling parts. When used as an aircraft gun, it was mounted both singly and in pairs on a Scarff ring.

If its date of production is taken into consideration, the Vickers-Berthier was quite advanced, as it proved to be a reliable, easily maneuverable, high-speed machine gun that served the needs of the gunner-observer firing from an open rear cockpit. It is an example, however, of what happens to any piece of aviation ordnance when change in design of aircraft makes it obsolete. This very reliable high-performance rifle-caliber machine gun is practically unheard of today, because, coincidental with preparations for World War II, British aircraft with power-driven turrets to take the place of the rear observer and his free gun were beginning to make their appearance. This act doomed all specially made free guns regardless of their state of perfection, as the turrets were all armed with belt-fed fixed-type weapons with higher speed, mounted in groups of two or more. Although the weapon was outmoded, England was so desperate for machine guns of any type that it was held in reserve for training purposes and the arming of armored vehicles. Manuals were printed on its use and maintenance all through World War II.

To fire the Vickers-Berthier aircraft machine gun, a loaded magazine is slipped into a recess

Vickers-Berthier Aircraft Machine Gun, Mk I, Cal. .303.

on top of the barrel until it engages its holding catches fore and aft. The charging knob, on the left side, is pulled to the rear and then shoved forward. The selector located at the right rear is turned to automatic fire. This cams down one of the two sears that lock the piston. The other is released when the trigger is pulled and permits the bolt to leave the cocked position.

Driven forward by the energy of the compressed driving spring, the upper face of the bolt strips a cartridge from the mouth of the magazine and starts to chamber it. During this act the extractor rides over the cartridge rim and snaps into the cannelure.

Coincidental with reaching its extreme forward travel, the rear of the bolt goes slightly beyond a locking step that is machined in the top of the receiver body. The bolt has an opening machined in its rear portion in which is riding the camming lug of the cross arm. This is all connected with a part of the gas piston. When the bolt reaches its locking recess, the speed and inertia of the piston cause the camming lug of the cross arm to engage a corresponding angle inside the bolt body, pivoting this part of the bolt up and against the locking step in the receiver body.

This swinging, or propping up, of the rear end of the piece removes the obstruction that has been holding back the cross arm on which the firing pin is attached. Being forced by the sudden pivoting of the rear portion of the boh body, the cross arm and firing pin can continue to advance with great speed for one-half inch. The firing pin then enters its tunnel and its tip smashes into the primer of the chambered round.

After the powder charge explodes and the bullet has passed a port about two-thirds of the way up the barrel, gas is admitted through a controlled orifice that acts on the face of the gas

Vickers-Berthier Aircraft Machine Gun, Mk I, Cal. .303, Mounted on a Scarff Ring.

piston. The latter's first movement rearward withdraws the firing pin tip from the primer, and after the cross arm is driven back approximately one-half inch, it disengages the two cams that are holding the swinging portion of the bolt against the locking step. The bolt assumes the horizontal in its slideway and starts to the rear.

A spring-loaded extractor withdraws the empty case and holds it close to the bolt face until the ejection slot is reached in the receiver. At this time the ejector fastened in the receiver collides with the base of the cartridge, pivoting and throwing it down through the opening to the right into a deflector for catching the empty cartridge. The spring-loaded magazine pushes another round in position and the recoiling parts continue on against the loading forces of the driving spring. Full recoil takes place when the moving parts make contact with a spring-loaded buffer that not only absorbs the surplus energy but accelerates the operating mechanism during counter recoil. If the trigger remains to the rear, the return movement results in repetition of the cycle.

Chapter 25
Lahti (Suomi) (L/S) Machine Gun

The Valtion Kivääritehdas (State Rifle Factory) at Jyäskylä, Finland, produced in 1926 a light machine gun that operated on the short recoil system. It was the invention of Finland's most outstanding automatic weapon designer. Aimo Johannes Lahti, who for a number of years was chief of this government arsenal. Lahti originated weapons for his country's use in all sizes from rifle caliber to cannon and, unlike most inventors, did not exploit a single basic system of operation but employed various methods ranging from short recoil to gas.

The Lahti (Suomi), or L/S, light machine rifle was one of his most refined models and was later used extensively by his countrymen in the Russian campaign. It was greatly respected by the Soviets and copied extensively by them. Ironically, while the Finns produced it primarily for sale either to England or to Germany, they were forced to use it first in defense of their homeland. The weapon, as modified in 1932, was given the factory designation, L/S Machine Rifle Model 26-32. It was air cooled and could be fired both full automatic and single shot.

The physical appearance of the weapon was practically the same as a standard army rifle and it was pointed out by the promoters that one infantryman armed with the L/S 26-32 could lay down as much fire power as an ordinary company firing the bolt-action rifle.

This weapon was produced originally for possible sale to the two major powers, England and Germany, which the Finns felt were potential enemies of each other. The weapon was chambered for each country's cartridge and it was especially designed so that, by merely switching the barrel and bolt, either cartridge could be used.

As evidence that the producers of the L/S 26-32 used this method of impartially seeking the business of both sides in any future war, a portion of a promotional booklet dated 1933 is quoted:

"The greatest advantage of this machine gun is that it at last solves the problem of a universal machine rifle of different calibers. It is designed so that after fitting in different operational parts the firing of cartridges of different calibers is possible. At present machine guns with firing mechanisms for British and German army cartridges are being made. During the manufacture, trials have also been made with 7.9-mm and 6.5-mm military cartridges and it was proved then

Lahti Machine Gun, Model 26/32, 7.92 mm.

the functioning and the accuracy of the weapon were equally good as with the above-mentioned cartridges. It is accordingly fully possible to chamber the weapon for every known cartridge powerful enough to operate its mechanism.

"It must be pointed out as a noteworthy fact, that for countries that use cartridges of different calibers, this machine gun has one great advantage in that it is built exactly in the same way for all kinds of cartridges, with the exception of the easily exchanged recoiling parts which must be changed, of course, on account of differences in chamber and bore measurements. To the recoiling parts belong the barrel, barrel extension and bolt.

"It must be remembered that the receiver is absolutely the same for all recoiling units, so therefore the operational parts are changed as one piece, because the barrel is rigidly screwed together with the barrel extension. . . . All bolts are exactly the same in appearance and dimension provided the cartridge rims do not differ too much. In that case the bolt must also be exchanged. For instance, when firing 7.92-mm, 7.7-mm, and 6.5-mm caliber cartridges it is not necessary to change the bolt because the difference in diameter of the cartridge rims is so insignificant with these cartridges that it does not cause any disturbance in functioning.

"There is another advantage which must be observed also and that is that in a state of war, in case of capture of any of the above kinds of cartridges, this machine gun can use the ammunition by putting in other operating parts in their own receivers. . . .

"These changes can be made during the actual fighting and they would only take some eight seconds to perform, provided the necessary operating parts are brought along by the machine gun section. Every state, however, knows its possible future opponent in war, and what kind of ammunition they will use and can always keep a certain number of exchange systems in stock."

The feed system is either a spring-loaded clip that holds 25 British caliber .303 or German 7.92-mm cartridges, or a flat drum magazine with a capacity of 75 rounds of the same ammunition. The weapon is chambered for either the British or German Army rifle cartridge, with a

Section Drawing of the Lahti Machine Gun, Model 26/32.

Lahti Machine Gun With Drum Magazine.

maximum rate of fire given as 500 shots a minute. The safety device operates so that, when the slide in front of the trigger is pressed back as far as it will go, a projection comes up under the sear. This makes it impossible to pull it down for release until the device is again moved forward.

For semiautomatic fire, the selector switch is moved off the safe position. As the trigger is pulled, the connector moves downward and draws the sear with it, releasing the bolt. Further pull on the trigger causes a nose on the front end of the connector to turn the latter around on the axle, whereby it is disengaged from the sear. This piece, under spring influence, engages its recess in the bolt before going forward to fire another shot.

The operator must release the trigger so that the connector may again engage the toe of the sear. Another pull on the trigger releases the sear to repeat the two distinct movements necessary for single shot firing.

To change either the conventional box-type magazine or the drum-shaped one, the magazine catch is pressed and the empty magazine removed by pulling down. A fresh one is then inserted, after observing that the holding catches are correctly engaged.

A loaded round cannot be left in the chamber of a hot barrel after a burst of long duration, as the bolt is automatically held to the rear after releasing the trigger. This not only prevents a cook-off but allows cool air to circulate through the open bore.

The barrel may be removed in a few seconds merely by turning the lever 180 degrees. This releases the catch holding the butt stock to the receiver. Then after lifting the receiver cover, the barrel extension with barrel and bolt can be pulled out to the rear. A cool barrel complete with extension and bolt is then inserted in place of the hot one. To prevent disassembly of the barrel and its hot members, the whole operating unit is changed.

To fire the L/S 26-32 light machine gun, the operator, if using the flat 75-shot drum, first removes the magazine support and pushes the drum up until its holding latch snaps. From the prone position, the charging handle is grasped by the right hand and pulled all the way to the rear. At this point the rising spring-loaded sear engages the notch in the bottom of the bolt, holding it to the rear. The weapon being cocked and ready to fire, the selector switch is moved from Safe to Automatic fire and the trigger pulled.

As the sear disengages the bolt, it is thrust forward by the energy of the compressed driving spring. The feed rib on top of the bolt shoves the first round out of the lips of the magazine and starts to chamber it. At a distance of one-half inch out of battery, the bolt seats behind the cartridge and the extractor claw snaps over its rim. At the same time the bolt-locking piece is cammed

down into its locking notch on the bolt and this act releases the holding device that has been keeping the barrel and extension to the rear.

The locked barrel, its extension and its bolt start final movement forward and at a point one-sixteenth inch from full battery position a pivoting pin in the tip of the bolt body that has been in the path of the retracted firing pin contacts a ramp in the receiver and is levered up out of the way. The firing pin is now released to fly forward, striking the primer. The timing is such that recoil forces of the exploding powder charge are set up before the fast traveling locked mass strikes the solid receiver, thus utilizing these forces to buff the action.

The recoiling parts are locked securely together for a distance of a half inch; the stud on the bolt lock then engages a cam in the receiver that lifts it out of its locking recess. The movement is done in such a manner as to allow the bolt to creep a few thousandths of an inch rearward before total unlocking. This permits the extractor to break the gas seal and fully loosen the cartridge during this phase. At the instant of firing, energy is transferred from the fast recoiling barrel to the bolt by means of an accelerator, which, upon pivoting, speeds the bolt to the rear with the extractor holding the empty cartridge case. When its rim strikes the solid ejector, it is knocked out of the slot in the right side of the gun.

The first recoil movement starts to jack the firing pin to the rear and continues to do so until its sear in the top of the bolt drops in front of the circular projection over the body of the pin. The barrel and its extension at the moment of bolt release is held in a retracted position by its holding latch. When the bolt has reached its final recoil stroke, compression of the driving spring starts it into counterrecoil to repeat the cycle.

Chapter 26
Rheinmetall-Borsig Machine Gun

Introduction

It is appropriate that the background of Rheinmetall-Borsig A. G., the giant of the German munitions industry in World War II, be outlined in order to help explain some of the reasons for the firm's mushroom growth.

On 12 February 1888 the directors of the already established firm of Horder Bergwerk of Westfalen, Germany, accepted a large contract to produce a new style jacketed bullet for the German Army. At the time it was decided it would be more satisfactory to have production of the bullets carried on by a separate company at another location. Consequently, a factory was completed at Derendorf, a suburb of Düsseldorf, on 13 April 1889. It was named Rheinische Metallwaren und Maschinenfabrik A. G., and on 7 May 1889 actual operations began.

The new company's technical adviser and vice chairman of the board of directors was Heinrich Ehrhardt, formerly a manufacturer of business machines in Düsseldorf and later famous as an ordnance engineer and inventor of gun mechanisms. The company prospered from government contracts for artillery and ammunition. A large volume of business for the same materials was also carried on with foreign governments, and at the outbreak of World War I Rheinmetall was second only to the great firm of Friedrich Krupp A. G. in the field of munitions.

During the conflict the company was engaged to the limit of its capacity in all kinds of ordnance production. It then began for the first time development and manufacture of machine guns, making, as did many other plants, the Maxim Model '08.

After the Armistice Rheinmetall's ordnance and munitions division had to be dismantled in accordance with Articles 168 and 169 of the Versailles Treaty. It was suspected and later confirmed that 23,000 tops of the firm's lathes, dies, drawings, and patents were shipped at this time to neutral Holland and stored in warehouses in both Delfzyl and Rotterdam.

In accordance with other clauses in the, treaty, the Inter-Allied Control Commission authorized the two firms, Krupp and Rheinmetall, to construct a limited number of weapons for the then small German Army and Navy. It was specified that the work was to be divided in such a way that Krupp would build all guns with a caliber over 17 centimeters and Rheinmetall all with this bore diameter and below. Krupp was thus confined to production of naval guns, since land cannon as great as 17 centimeters were forbidden to Germany. Consequently, all army weapon development fell to Rheinmetall and between the years 1925 and 1927 the company was permitted to install, subject to Inter-Allied supervision, the many special facilities necessary to carry on such activities.

From this point on Rheinmetall began to formulate plans that would put it in a position to regain its lost world trade. An attempt was made to establish a subsidiary company in Holland under the name of Hollandische Industrie und Handels Mattschapv (HIH), but this venture turned out to be anything but satisfactory. With the severance of its Dutch connection in 1929, Rheinmetall acquired ownership of a concern when known as Waffenfabrik Solothurn A. G. in Solothurn, Switzerland.

This Swiss plant originated as a watch-making concern. Following the war the company had trouble keeping solvent because of the slump in that industry. It was sold at a sacrifice to a Swiss citizen named von Steiger, who previously had been a director in the Deutsche Waffen- und Munitionsfabrik A. G. of Germany. Von Steiger left the employ of D. W. M. when the enforcement of the disarmament clauses in the Versailles treaty by the Inter-Allied Control Commission ended its activity by completely dis-

mantling this mighty automatic weapon manufacturing company.

The new owner converted his establishment to the making of cartridges for small arms and failed financially a short while later. The factory was then taken over by Fritz Mandl of Hirtenberg, Austria. The Solothurn plant, upon passing into Mandl's control, was immediately converted to the manufacture of various types of small arms. It was with Mandl that Rheinmetall dealt in purchasing the Solothurn plant in order to control a weapons factory in a neutral country free from Allied restrictions.

In accordance with the terms of purchase, Fritz Mandl was retained in 1929 as director of the new subsidiary of Rheinmetall. Since the parent company was 51 per cent owned by a German Government holding corporation, and as 90 percent of the ownership of Solothurn was in the hands of Rheinmetall, it can be readily seen that the German military authorities could control its policy. Through the Rheinmetall offices in Berlin, an agreement was also worked out with a large armament factory in Austria and similar contracts were also made with other manufacturers, particularly in Austria and Hungary, for production of component parts of automatic weapons.

It is incredible that in a matter of months after being taken over by the Rheinmetall firm, Solothurn, with its limited facilities, could have manufactured all the weapons known to have been sold bearing its name. Actually it has been found that Solothurn procured the necessary components from inside Germany and Austria and used the plant primarily as a place of assembly.

In this manner it served the holding company well. It allowed Rheinmetall to sell not only to nations friendly to Germany, but also to politically hostile ones which needed armament but dared not arouse public opinion at home by buying munitions directly from a German firm. Both Solothurn and the customer nation found it agreeable to hide at the moment behind the shield of Switzerland. Apparently only the Germans knew exactly what was going on, as it will be noted they always possessed a weapon superior to the one being offered for sale. In other words, they could see no harm to the Fatherland in allowing the rest of the world to pay for experimental and development work while they prepared for another war.

Solothurn Model 29

Within 2 months after its sale to Rheinmetall was approved on 4 April 1929 by the stockholders of the old company, Solothurn offered a new machine gun, Model 1929, to the military powers of the world. This would have set an all-time

Solothurn Machine Gun, Model 1929, 7.92 mm.

Drawings Showing Stange's Action.
Top: Bolt in Battery, Locked, Ready to Fire.
Center: Gun Fired, Barrel Recoil Rotating Locking Ring.
Bottom: Locking Ring Fully Rotated and Bolt Unlocked.

high for conception, design, and production had the Solothurn craftsmen actually done this. The truth of the matter was that the weapon was originated and developed at Rheinmetall by Louis Stange, who is rated among the best of Germany's many fine automatic arms designers.

Stange first started work in the Theodor Bergmann arms factory at Suhl as an apprentice of Louis Schmeisser, one of the most prolific creators of sound automatic weapon systems in all Europe. They included self-loading pistols and submachine guns in addition to refinements on already existing mechanisms. Schmeisser, like Stange, became affiliated with Rheinmetall and assigned many of his patents to this company.

Most of Germany's other talented mechanics who had shown their ability to produce successful automatic gun mechanisms were also on Rheinmetall's technical staff. The most outstanding of these designers were Karl Heinemann, of Berlin, developer of the Parabellum action in World War I, Fritz Herlach, Karl Voller, Alfred Krum, all of Düsseldorf, and Herman Henning and Wolfgang Rossmanith, of Berlin.

These names are given to show the significance of the following statement made by Solothurn in literature announcing its debut in the gun-producing business:

"The Waffenfabrik Solothurn A. G., of Switzerland, is authorized to copy and reproduce all patterns of construction of the Rheinische Metallwaren und Maschinenfabrik A. G. (Rheinmetall-Ehrhardt), of Düsseldorf, Germany."

With the financial backing and the design genius that was thus made available to the small plant located outside of Allied jurisdiction, there is little wonder that many fine weapons began to make their appearance bearing the name "Solothurn."

The Solothurn Model 1929 was an air-cooled, short-recoil-operated machine gun of very light construction, weighing only 17 pounds. The barrel was chambered for the German 7.92-mm infantry rifle cartridge. It was of extremely simple construction with few component parts. These pieces, as the promoter pointed out, were machined almost exclusively in lathes. Thus the manufacture of spare parts would offer no difficulty to any government that purchased them. South American countries were particularly interested in them because of being able to make needed replacement parts in their own machine shops.

The bolt was cylindrical in shape with a central locking ring rigidly holding the bolt and barrel together by means of six interrupted threads. The striker was enabled, by the removal of the obstruction at the time of locking, to continue on into the primer of the cartridge. This method was known as timed inertia firing. When the magazine was emptied by the discharge of the 25 cartridges, a catch then rose and held the bolt in the cocked position. It also warned the operator that it was necessary to place a fresh magazine in position. The safety was a device that locked bolt and trigger together, allowing the insertion of a loaded magazine with the bolt locked on safe.

Single shots, or automatic firing, of the Solothurn Model 1929 could be accomplished without interrupting the gunner's aim. The operational energy was derived from the recoiling masses. Under heavy strains brought about by abnormal testing conditions, the mechanism proved to be very reliable.

MG-30

These weapons had hardly been made available when Solothurn--as Rheinmetall's outlet-put on the market a more refined version, designated by the factory the S-2-200, and by the German Army the MG-30. Its method of operation was basically the same as that of the earlier model.

A considerable number were sold to European governments. Austria, for instance, adopted the gun in 8-mm bore, calling it Model 30; while Hungary put it into her service with the designation, Model 31. In the next 5 years these nations alone purchased over 5,000 S-2-200 light machine guns. That the two neighboring countries accepted this type is quite understandable since the Steyr arms factory, in Austria, is credited with furnishing everything about these weapons except for assembly, which was done at Solothurn.

As with the earlier model, when the last shot was fired, the bolt stayed in a retracted position. The loaded magazine could be inserted

Solothurn Machine Gun, Model 1930, 7.92 mm.

regardless of the position of the bolt. Two circular depressions were cut one above the other on the front face of the trigger. Pressure on the top one gave single shot operation, while a pull on the lower portion delivered automatic fire. This permitted the operator to change from one to the other without interference with his aim.

The barrel of the MG-30 also was air-cooled, but a different provision from that of the earlier versions was made for changing it. The switch from a hot barrel to a cool one was done in a quick and unique manner. The shoulder piece was moved from the receiver by pressing on a locking spring. The stock was then turned 60° to the left and pulled backward, the driving spring and its guide remaining in the rear housing. The barrel, with the attached bolt and carrier assembly, then were shaken out of the receiver to the rear. The assembly was disconnected from the hot barrel and placed on a cool one. The replacement was then inserted in the jacket and the procedure reversed.

The German Army ran a 100,000-round test on the model and reported very good results. However, it was not adopted for general service, although many were used for drill purposes.

When the MG-30 is fired, the barrel, bolt, bolt extension, mainspring guide, and locking ring move backward under action of recoil as a rigid assembly with respect to the receiver. At a predetermined distance, the rollers on the locking ring engage the spiral groove in the walls of the receiver.

Further rearward movement turns the locking ring and unlocks the bolt. At this point the recoiling of the barrel, bolt extension, and locking ring is checked by a buffer and they are held in this retracted position. The bolt and mainspring guide now move rearward under the accelerated force imparted by the spiral grooves, as the extractor withdraws the empty cartridge. Further recoil ejects the case and compresses the main driving spring. When these parts have reached the extreme distance they can travel, counter recoil commences.

As the bolt moves forward, it picks up a round from the magazine and chambers it. The bolt, being seated in its carrier, pushes the carrier, barrel, and locking ring forward. The latter, turning under the influence of its lugs, engages the spiral grooves and locks the assembly. When the bolt first starts into counterrecoil movement, a sear engages its notch in the firing pin, holding it while the rest of the assembly continues on to compress the firing-pin spring. The final movement of going into battery automatically releases the firing pin.

MG-15

In 1932 Rheinmetall presented the German Air Force two weapons that were the outgrowth

Rheinmetall Aircraft Machine Gun, Model 15, 7.92 mm.

of the MG-30. Both were rifle-caliber aircraft machine guns and were given the designations, T6-200 and T6-220. They were promptly adopted by the German aviation section the following year and officially named the MG-15 Fixed and MG-15 Flexible.

Only minor modifications were made from the MG-30 to adapt them to aircraft use. If examined closely for comparative purposes, there was no difference in the basic action of these weapons and of Stange's earlier models. The rate of fire on the aircraft version, however, was increased from 750 to 1,000 or more shots a minute by the employment of a muzzle booster with a restricted orifice. Ammunition was carried to the fixed gun by means of a metal disintegrating belt. An odd but efficient recoil-actuated ratchet-type feed system indexed each round and could feed from right or left, as desired, by the mere repositioning of parts.

On the MG-15 Flexible gun, ammunition was fed from a twin-drum magazine, holding 75 rounds. The cartridges were lodged in two containers fitted to the right-hand and left-hand sides of the gun. In this system of cartridge feed by twin drums, the two halves of the drum were alternately emptied, so that the center of gravity was not affected by the gradual emptying of the container. The magazine could be changed with one hand in a very short time.

The MG-15 Fixed gun would fire on an average of 200 rounds a minute faster than the one with flexible mount. This was due to the rigidity in mounting the stationary gun that could utilize more of the recoil force of the exploded powder charge. The fixed gun was also easily adapted to fire between the propeller blades by use of a synchronizer. One particularly bad feature about the wing installation, however, was that, in the event of a condition known as a runaway gun, no provision was made for stopping it and uncontrolled fire would continue until all ammunition was expended.

MG-17

The German Air Force decided that, while the lightweight high-speed MG-15 had many good features, it could still be made more suitable for aircraft use if it were not rear seared after each burst, since this presented a serious synchronizing problem. The cocked bolt was considered essential in designing ground-type weapons in order to leave the overheated chamber empty after each burst and prevent cook-off of the loaded cartridge. It was not considered a critical factor, however, in aircraft installations. The fixed weapons could be cooled with high velocity air by ventilation and, if a cook-off were to happen, there was little danger of the bullet striking friendly materiel or personnel. In addition, guns were being mounted in the wings out-side the propeller arc and were divorced from any attention or maintenance from the pilot

Rheinmetall Aircraft Machine Gun, Model 17, 7.92 mm.

gunner. This necessitated the use of devices that performed the functions of charging and firing the weapons by remote control.

With these problems in mind Rheinmetall designers made several improvements on the original MG-15 by modifying it so that it could be loaded and cocked by means of a charging device. It was actuated by compressed air and then fired by an electrically controlled trigger contrivance called a solenoid.

In older that this closed-bolt firing version operating by remote control would not be confused with the models not having the above modifications, this machine gun was officially known throughout the German armed services as the MG-17. Other than the refinements mentioned.

Components of the Rheinmetall MG-17.

there was no difference between it and similar Rheinmetall guns that preceded it.

The abnormally high speeds demanded of aircraft machine guns made head-spacing a critical dimension. Provision was made on this gun whereby an ordnance man in the field could arrive at this measurement quickly and efficiently by use of a case-hardened gage. The instrument was made in the form of a cartridge to be inserted in the chamber. The bolt latch was raised and the bolt lock rotated until pressure was felt. It was also necessary, when head-spacing the MG-17, to make a compensating adjustment on the solenoid. Consequently, they were manufactured with four choices of measurements designed to take care of any permissible head space movement.

The charging device was operated by compressed air, the planes first being equipped with small compressors that operated off the main engine and later with cylinders that were charged on the ground. Carbon dioxide bottles were also used but it was found that, although this method was most efficient under certain conditions, it had a tendency to freeze up the mechanism of the charger, because of the extremely low temperature of the expanding gas.

MG-131

Shortly after the introduction of the MG-15 by the German Air Force, negotiations were started for the amalgamation of Rheinmetall with then bankrupt Borsig works, which had an enormous well-equipped plant at Tegal, a northern suburb of Berlin. In the past the firm had made locomotives and other heavy steel fabrication. On 1 January 1936 the deal was completed and Rheinmetall-Borsig A. G. first came into existence.

Hitler then held full power over Germany and Herman Goering had been given the responsibility of building up German aviation might. One of Goering's first official acts was to make a former World War I squadron mate chairman of the new corporation's board of directors. This officer was Rettmeister Bolle, a much decorated fighter pilot, and he sought to show the fatherland that he was worthy of the "Pour Le Merite" by introducing improved aerial weapon design.

The German Air Force well realized its need for a high-speed light machine gun chambered for a caliber larger than the standard rifle cartridge. As soon as the restrictions placed upon them by the Allies were lifted, a directive from Goering to the Rheinmetall-Borsig firm ordered it to develop and produce a suitable weapon in this category. The resulting machine gun was given the official marking, MG-131.

This belt-fed, air-cooled weapon weighed only 40 pounds, and had a rate of fire officially accepted as 960 rounds a minute. The most important thing, as far as the Germans were concerned, was that it was chambered for a specially constructed 13-mm cartridge propelling a bullet with the high velocity of 2,560 feet. In addition to being light and reliable for its larger caliber, another advantage was the use, in place of a standard percussion striker, of a spring-loaded firing pin that detonated the primer by means of electricity. The greatest benefit of this method of detonation was for synchronization and fire interruption.

Although Louis Stange first started work on such a gun in 1933, it was not until Germany was on the threshold of war in 1938 that the weapon made its debut, and then in the greatest secrecy. Germany wanted her potential enemies to believe she still had nothing larger than the 7.92-mm aircraft machine gun.

Its initial appearance was in very limited numbers for paired installation in turrets, being the first heavy caliber machine gun to be used in a German land plane. A pair was mounted in a power-driven turret on the DO-217E2. This plane also carried another MG-131 in the rear central position, which, however, was operated manually.

The feed system was interchangeable from left to right, and vice versa, by repositioning of parts. Empty cases were ejected through a slot in the bottom of the receiver, a very necessary feature for aircraft use. Cocking, when done by hand, was accomplished by use of a ratchet handle that required 8½ strokes for full retraction of the parts. When not in operation, the handle, which was the invention of Georg Engel and Alfred Winter, two Rheinmetall engineers, folded down out of the way and was shoved for-

Rheinmetall Aircraft Machine Gun, Model 131, 13 mm, Fixed.

ward. It could be changed if need be from one side to another.

When the bolt was locked to the barrel, as in battery, it required more energy than most individuals possessed to pull the action back against both the driving and barrel springs until the rotary locking ring released the bolt. This made necessary a hand-charging arrangement, so constructed as to give the gunner great mechanical advantage when performing this act.

A metal disintegrating push-out-type link belt was always employed in getting ammunition to the feedway. No provision was made for single shots with this weapon. When the selector switch was turned on, the result was full automatic fire only. The buffing system was new in relation to earlier models. It used multiple springs in order to dampen the shock and friction by acting as a brake shoe upon a sleeve which is locked to the receiver.

The mechanical safety device took the form of a lever which rotated the sear lock in the path of the sear and also cut off the electrical detonating current. Ahead of the stationary receiver there was housed the barrel return mechanism, which in addition to the heavy ring spring comprised a rotating locking sleeve and a coupling device between the barrel and breech. The rear end of the receiver contained the bolt and driving spring.

The ammunition feed system indexed each round half by recoil and then completed the operation by counterrecoil. Two sets of rollers in the cover group engaged ramps machined along the top of the bolt. When feeding from left to right, the bolt being in recoil, the outboard rollers would climb the inclined surface on the bolt and cause the outer feed pawl to index a round into position for stripping. The center pawl meanwhile was extended its full throw to snap behind the next round.

When the bolt started back to battery after having picked up the positioned round from the feedway, it would cam up the inboard set of rollers. This movement retracted the center pawl, moving the incoming round over one half space and at the same time sliding over the outside pawl behind the cartridge. When the cycle was repeated, the recoiling movement of the bolt completely indexed the incoming cartridge which was then chambered by counter recoil. This simple method relieved the bolt of high side loads and resulting friction usually found in track-type feed levering systems.

The MG-131 had Stange's patented locking ring with several added features that, while not original, were somewhat radical in design. For instance, barrel recoil was speeded up by a gas booster, which in turn transmitted energy to the bolt by a pivoting accelerator acting on the under side of the bolt at the instant of unlocking. The barrel, after three-fourths inch of recoil, was held in the retracted position by a sear device that was tripped only after the bolt contacted the barrel, allowing the parts to lock on the way into battery. This permitted the timing

Rheinmetall Aircraft Machine Gun, Model 131, 13 mm, Flexible.

of the firing mechanism whereby the powder charge could be exploded and recoil forces set in a few hundredths of an inch before the fast and heavy moving parts collided with the rear end of the stationary receiver. In high-speed weapons especially, the act of buffing the action on counterrecoil not only insured longer parts life but gave smoother performance.

Another of Stange's typical features on this weapon was that the forward top surface of the bolt was movable up and down and spring loaded so as to remain in the up position. He had noticed that, in order for the incoming round not to interfere with the bolt body when being moved into position, a long bolt stroke was necessary. Sufficient distance was thus given for it to be moved into place after the bolt had recoiled beyond the base of the round in the feeder. The new device permitted a shorter stroke and raised the cyclic rate.

As the bolt, with its pivoted, spring-tension top recoiled, the cartridge was indexed in the stripping position and as the movement continued, the top came in contact with the under side of the cartridge case to depress the pivoting surface of the bolt. It slid easily under the round and as soon as the bolt face cleared the rim of the cartridge, the spring snapped the front part of the bolt face up to push the base of the cartridge out of the link.

Ammunition for the MG-131 consisted of either high-capacity explosive bullets or armor-piercing ones containing incendiary or tracer elements in the base. The explosive bullet had a supersensitive impact fuze that was completely bore-safe. The armor-piercing bullet was unusual in that it employed a rotating band and the tungsten-hardened projectile was not enveloped in a gilding metal jacket.

The German Air Force held the MG-131 in high regard. At the outbreak of the war, when its fighters found themselves with only 7.92-mm guns attacking British bombers armed with Browning caliber .30, the situation called for immediate installation of the high-speed 13-mm weapon in all attack planes. Eventually it too became obsolete from the trend to automatic weapons of even higher cyclic rates, capable of firing a shell with considerably more bursting charge.

The MG-131 was produced for the German Luftwaffe by these firms: Rheinmetall-Borsig, of Berlin; Deutsche Waffen- und Munitionsfabrik A.G., Posen; I. C. Wagner, Muhlhausen; and Heinrich Krieghoff Waffenfabrik, Suhl.

To fire the weapon, the gunner first positions a loaded belt in the feedway and, if it is to be manually operated, jacks the ratchet-type cocking handle back 8½ strokes until the rear sear engages its recess in the bottom of the bolt. By actuating the solenoid, the sear is disengaged and the operating parts sent forward by the driving spring. The pivoting member on top of the bolt strikes the indexed round, driving it into the chamber. The bolt assembly, moving forward, contacts the barrel and a camming angle on the left side of the bolt engages the barrel release catch, forcing it down. Upon being freed, the whole assembly starts toward battery under tension from the heavy barrel return spring, and the bolt and barrel are locked together as the locking ring is rotated one-quarter turn clockwise.

On the right side of the receiver near the breech end of the barrel is an electric switch. It energizes the circuit when the whole counter-recoiling mass is one-sixteenth inch out of battery. The weapon then fires and recoil forces start in before the bolt and barrel strike the receiver. With the building up of the peak powder pressure and for a half inch of free travel during recoil, the bolt and barrel continue rearward as one unit. The lugs in the receiver then rotate the locking ring a quarter turn counterclockwise and unlock the recoiling parts. The barrel hold-back device is thereby forced out, retaining the barrel in its retracted position. Coincidental with the unlocking, a pivoting accelerator located in front of the bolt transmits the energy of the recoiling barrel to the bolt face and speeds this part to the rear.

After initial extraction, the extractor withdraws and holds the loosened round until, upon contact with the ejector, it is kicked through the bottom of the receiver. The bolt continues towards its rear buffer. The recoil feeds a cartridge over one-half space, and in counterrecoil it is completely indexed. The driving spring, now being fully compressed, throws the bolt into counterrecoil, and as long as the solenoid is energized, the cycle of operation is repeated.

Chapter 27
Scotti Machine Gun

In 1928 there appeared the first of a series of machine guns by an Italian designer named Alfredo Scotti, who maintained offices in Brescia, Italy. In practicing his profession, Scotti always depended upon companies with manufacturing facilities to make and promote the sale of his weapons on a contract and royalty basis. His place in design history rests upon the exploitation of a single principle or system. In itself, it was not original, being based solely on the act of unlocking by rearward movement of a gas piston at a time when a high enough residual pressure remained in the chamber to complete the cycle of operation. While automatic firing mechanisms bearing the name of Scotti range from pocket pistols to cannon, they all have the rotating bolt head actuated by a gas piston.

A number of firms have been associated with weapons designed by Scotti. The Grandi Co., located at Solbiete, Italy, near Milan, manufactured many models for test including sub- and light machine guns and a 20-mm cannon. The Ansaldo firm in Italy produced a light machine gun and a 37-mm automatic cannon that was entered without success in an Italian Navy test in 1931. The main producer of Scotti's models was the Isotta-Fraschini Co., Italy's largest automobile and aircraft engine manufacturer. It fabricated one or more models of 30-mm cannon and several aircraft machine guns ranging in bore from 6.5 to 12.7 millimeters. Guns made by this company in 7.7 and 12.7 millimeters were used to a limited degree by the Italian Air Force throughout World War II.

Scotti's activities were by no means confined to his native land. To handle the manufacture and sale of his weapons in all countries outside of Italy, he established Scotti-Zürich, a firm in Zürich, Switzerland. Some of the main components for these guns were made by the Swiss firm, Oerlikon, while lesser ones were obtained by contract from the Swiss Industrial Society at Neuhausen. In November 1932, Oerlikon purchased outright Scotti-Zürich, including all foreign rights to Scotti-type guns. Italian rights were reserved by Isotta-Fraschini.

The only variations in Scotti guns were in size and external appearance. The most radical of his designs on record was his triple-barrel machine gun, made in bores of 6.5 to 8 millimeters. It employed a handle to rotate a fresh barrel into position, thereby allowing the gunner to keep up continuous fire by having a cool barrel available at all times. While this may have seemed very original to Scotti and he was given a patent on it, both he and the patent researchers must never have seen the specifications of the hand-operated Lowell gun, recorded in the United States in 1875.

Scotti Aircraft Machine Gun, 7.7 mm.

Drawing of Scotti's Action.
Top: Bolt in Battery and Locked. Slide in Forward Position to Prevent Bolt Head from Rotating.
Bottom: Slide Retracted by Gas Piston, Allowing Bolt Head to Rotate and Unlock.

On one model Scotti used a feed system that had been patented previously by another Italian, Giuseppe Perino, in 1901. This method of feeding was accomplished by a metal strip housing each cartridge individually. The bolt pushed the loaded cartridge out of its housing and after being fired, replaced it in its original position on recoil stroke. The metal clip was indexed over one space after each shot and was ejected completely out of the right side when the last round was fired.

To fire any weapon of the Scotti system, the operator installs a loaded belt, strip, or drum, as the case may be, and pulls the firing mechanism to the rear by the charging handle. This first movement unlocks the bolt and retracts the firing pin. The assembly is held in the cocked position under tension of the compressed driving spring. By actuating the trigger, the sear is released and the bolt starts home, stripping a round out of the feedway, and pushing it ahead as the two-piece bolt starts into the last phase of chambering the round. Lugs on the forward part engage cams in the barrel extension, giving the bolt head a fraction of a revolution turn and locking the barrel and bolt head together.

The firing pin is housed inside the bolt and is attached to slides that, upon removal of the obstructing lugs, are forced forward by both inertia and driving-spring pressure. The firing pin is directed into the primer which detonates the propellant charge. When the projectile passes a port in the barrel, sufficient gas is bled into a cylinder that houses the gas piston. This closely metered gas gives the piston a slow backward thrust movement at just the right instant to permit contiguous slides to move rearward, allowing the bolt head to rotate while a high residual pressure remains in the bore.

The locking lugs being inclined at an angle of 60° make unlocking require little energy, as the gas pressure acting on the face of the bolt would rotate the lugs and unlock were they not covered by the slides. The latter having retracted the attached firing pin, the whole mechanism starts to the rear, with the operational force now

Scotti Aircraft Machine Gun, 12.7 mm.

coming from the remaining gas, or blow-back. The empty lubricated cartridge case, being held to the bolt face by the extractor, slips back with the recoiling bolt and is pivoted out of the receiver upon making contact with the ejector.

The bolt continues to recoil until stopped by contact with its spring-loaded buffer and compressed driving spring. If the trigger continues to be depressed, it then starts on its counterrecoil stroke to repeat the cycle of operation. Release of the trigger pressure causes the sear to rise and engage the recess in the rear of the bolt, holding the entire bolt assembly to the rear.

While this action was undoubtedly retarded blow-back, it should not be confused with other methods, particularly of Italian origin, where the whole bolt assembly creeps rearward at the instant of firing and opens up progressively afterwards. The Scotti principle positively locked the bolt and barrel together and the gas bled into the cylinder was for the purpose of unlocking only. This system most certainly was not new, as Mannlicher used it successfully and patented it in 1899, even to the rotating bolt head for unlocking. However, Scotti gave it greater use, as he employed it in everything from hand gun to cannon.

Chapter 28
Bang Aircraft Machine Gun

The Danish Rifle Syndicate of Copenhagen, Denmark, in 1929 formed a company to produce a caliber .276 flexible aircraft machine gun to be known as the Bang. The weapon was the invention of Soren Hansen Bang, an employee of the Syndicate. It used a method of capping the muzzle with a cone-shaped device.

This system was by no means new, having been patented by Sir Hiram Maxim and used successfully by John M. Browning on his first experimental model in 1889. Its main drawback was that it demanded many clumsy accessories to accomplish very little. Even the preliminary operation was only begun well after the bullet left the bore, which made the method notoriously slow. After one working model was constructed and factory tested, the project was dropped. There is no record of another of the Bang aircraft machine guns being made.

The method of firing the weapon is as follows: After a loaded magazine is put in place and the action charged, a pull on the trigger fires the piece. The bolt remains securely locked behind the base of the cartridge until the bullet leaves the bore. The muzzle has a cone-shaped device that can slide parallel with the barrel and is attached by means of rods to the locking system.

The expanding gases are trapped in the cone after the bullet is clear. This sudden explosion in the cone jerks it forward and, in doing so, unlocks the breech.

Helical cuts on the inner surface of the receiver act as opposing angles on the bolt and rotate the bolt out of the locked position. It is then accelerated in recoil by the trapped gas pressure acting on the base of the cartridge driving the bolt assembly to the rear at high speed. The compression of an unusually stout driving spring absorbs all surplus energy and puts the operating parts in counterrecoil.

Bang Aircraft Machine Gun, Cal. .276.

Chapter 29
Sistar Machine Gun

On 3 December 1932 there was filed in the Italian patent office an application covering the design of a recoil-operated machine gun, which, according to its inventor, Niccolo Mancini, of Florence, Italy, was a decided improvement on existing automatic firing mechanisms.

Not having the financial means to exploit his invention, he placed it with the Sistar Co. in Florence. Sistar actually was not a producing organization but a promotion and design firm which specialized in developing and financing likely looking patents. By this business connection, Mancini gained all the prestige needed to call on interested parties. He was made president of Sistar's machine gun section, a title that no doubt was more impressive than the salary.

Demonstration machine guns were produced, both in light and heavy models. While the operating mechanisms were identical, the two types varied in the following characteristics. The light gun chambered the 6.5-mm infantry rifle cartridge; the heavy the 7.92-mm Mauser type. The light gun with its 22 pounds was half the weight of the latter, and the rate of fire was 700 rounds a minute on the small weapon and 500 on the other. The magazine on the lightweight

Sistar Heavy Machine Gun, 7.92 mm.

Sistar Light Machine Gun, 6.5 mm. The Operator Is Loading the Magazine.

version held 20 rounds, while the other utilized a semi-rigid metal belt holding 250 rounds wound on a drum.

The light machine gun, while having only a 20-shot magazine, did have a feature that the company made great effort to demonstrate on every occasion. The gunner, without rising, could pivot the swinging magazine forward from the prone position and insert in a matter of seconds a fresh supply of loaded rounds directly from the cardboard container into the feed system. By this ease and speed in loading he could keep up practically uninterrupted fire.

The weapon was recoil operated, the barrel having an open jacket that gave it support and a bearing for "floating" the recoiling parts. The barrel return spring was housed inside this skeletonized jacket. A large charging and carrying handle was located on the left side considerably forward of the usual placement of retracting assemblies. The trigger was placed underneath and slightly to the right. However, the customary guard, to protect it from accidentally striking some object and discharging the piece unintentionally, was omitted.

The recoiling parts were housed completely in a boxlike receiver on the top of which was a graduated sight. Air cooling was provided by circular fins machined along the barrel to give greater surface for heat radiation.

A built-in oil pump on the left side of the receiver sprayed a small jet of oil on the incoming rounds as each was positioned for chambering. This device was actuated by the recoil and counter-recoil movement of the barrel extension.

The heavy machine gun had identical operating parts, but most certainly did not resemble the lighter gun in any other way. Its cooling was by air, but the barrel housing resembled the conventional water-cooled jacket. Long aluminum tubes grouped around the barrel were supposed to dissipate heat more efficiently. The 7.92-mm ammunition was fed to the weapon in a belt using push-out-type links, also originated and patented by the inventor of the gun. A clumsy looking handle with unprotected trigger was used on this heavy Sistar machine gun.

Both versions appeared only in prototype form. While many of the principles have later been proved sound, especially the locking method, apparently nothing was ever done to develop either one. There is no record of any extensive test conducted either by the factory or the government. Consequently, it had a very short-lived competitive existence.

To fire the lightweight 6.5-mm gun, the operator first assumes the prone position and with his right hand releases the catch allowing the swinging magazine to pivot forward. This leaves

Sistar Light Machine Gun, 6.5 mm. The Operator Is Charging the Weapon.

the rear part open for inserting the front end of the 20-round cardboard cartridge container. After positioning it in the magazine mouth, finger pressure forward shoves the cartridges from the box into the spring-loaded magazine. When filled, the empty container is then thrown aside and the loaded magazine is swung back and latched securely in the ready position.

The operator then grasps the barrel retractor with his left hand and the bolt charging handle with his right, and simultaneously pulls both fully rearward. This unlocks the piece and compresses the driving spring. Upon being released at the rear the bolt assembly goes forward to battery while stripping a round from the magazine, chambering it and locking the piece for firing.

With the safety off, pressure is put on the trigger and the striker flies forward under spring compression to ignite the primer. As the powder gases are reaching peak pressure with the bullet still in the bore, the barrel, bolt, and barrel extension are securely locked and continue to be for a travel slightly over a half inch. The breech lock, pinned to the recoiling barrel extension, then rides up a ramp machined in the top of the stationary receiver. The end of the breech lock is pivoted up, unlocking the bolt and allowing it to continue rearward free of the other recoiling parts. The barrel driven by its strong spring returns to battery. This gradual freeing of the bolt allows the extractor to pull the empty case free, insuring initial extraction of the fired case before complete unlocking gives it a snatching movement.

The bolt, continuing rearward, carries the empty case held in position by the extractor until the base of the cartridge case strikes the ejector. The latter pivots and kicks it out of the ejection slot on the left side.

The bolt, at its rearmost position, compresses its spring buffer and then is driven forward. The rebound off the buffer, in conjunction with the driving spring, located in a housing offset to the left of the operating parts, starts counterrecoil. As the bolt face passes the mouth of the

magazine, it pushes the indexed round ahead of it into the guide way of the chamber. The firing pin assembly at this point has been traveling with the bolt as a unit, but at a distance of 1 3/4 inches out of battery a spring-loaded sear located on the back of the breech lock lever engages the front face of the striker housing, holding it back while the bolt continues to go on into battery.

At this point, if the trigger button is still depressed, the breech lock in reaching its recess pivots down in front, securely locking the barrel, barrel extension, and bolt together at the same time. The sear on the back of the breech lock lever is raised, freeing the firing pin it has been holding in the cocked position. The pin flies forward and again fires the piece. If trigger tension is not applied, the breech lock will still release the firing pin but instead of flying all the way forward it will merely snap forward a few thousandths of an inch and come to rest on the trigger sear. Further actuation of the trigger is needed to release it.

The United States Government in 1935, upon hearing from officials of the Sistar Co. of the various advantages this machine gun had over others, requested its attachés to report on the performance of the gun and what it had to offer. Upon investigation it was found that the Sistar firm as a manufacturer was non-existent and that the few models that were then being used for limited demonstration were produced by hand in various job shops. All available models at the time were in Rome where they were being given consideration by the Italian Government for purposes of adoption.

Italian authorities, however, did not see fit to produce this weapon for either air or ground use, and it never got beyond the prototype stage in development. The army, with its partiality to the retarded blow-back system, held in disfavor the Sistar's straight-recoil operation.

Chapter 30
Knorr-Bremse Machine Gun

Swedish military authorities, upon becoming interested in a strangely designed machine gun, invented by Hans Lauf of Charlottenburg, Germany, had their government small arms factory manufacture the weapon for testing purposes in 1933. Lauf, in presenting it, described it as a gas-pressure-operated machine gun and made many claims for the unusual contrivance. The inventor was well known in the gun world and at the time was a director of the Knorr-Bremse Manufacturing Co. of Lichtenberg, Germany. However, since the Swedes showed initial interest, he permitted them to manufacture the first models with the understanding that, if adopted, he would receive royalties.

These Swedish-made weapons were given the designation L. H. 33, the markings probably being specified by Lauf to include the initials of his name and the year produced. After extensive trials the authorities did not see fit to adopt the weapon and Lauf turned to the Knorr-Bremse company to produce and promote it commercially.

The firm made a limited number and Lauf bent every effort to interest representatives of many countries, giving personal demonstrations in each instance at the Knorr-Bremse firing range at Tegel to show off the good features claimed for the gun. The weapons made by the German company were officially labeled Knorr-Bremse 35/36. Those who witnessed Lauf's firing demonstrations failed to observe any features so outstanding as to warrant more investigation. The design was by no means revolutionary nor did it contribute a performance superior to that of the many tried and proved weapons of the time.

The barrel on this gun was very short and, due to this fact, even when an oversize flash hider was employed, it still had enough brilliant flame at the muzzle to impair aiming. The balance of the weapon was exceedingly poor and the absence of a wooden forearm made it impossible to discharge the piece in any other way than in the prone position with the use of a bipod because of the heat. The excessive length of the heavy stock also resulted in an undesirable distance to the rear sight.

Firing from a cocked-bolt position, with the mechanism being held back by an unusually strong spring that was supposed to help dampen

Knorr-Bremse Machine Gun, Model 1933, 7.92 mm.

Components of the Knorr-Bremse Machine Gun, Model 1933.

recoil, made the gun lurch forward each time the action slammed home on single shots, with a natural destruction of accuracy. And while the barrel could be changed rapidly, the machined clearances on its components, that had to be removed first to make this change possible, resulted in considerable gas leakage.

The 25-shot magazine, when filled and inserted into the left side of the gun, made the weapon "left-heavy," and threw the gunner's aim off during first stages of automatic fire.

On the favorable side, a very novel feature was that by merely pulling the trigger at its top portion it could be changed from single shot to automatic fire. This piece was pivoted in the center and its depression at the bottom resulted in a full automatic burst. The cost of manufacturing the components was reasonable due to their simple construction. The barrel had longitudinal ribs that not only gave more rigidity but also furnished more cooling surface for heat dissipation. In the entire assembly there were only 62 components, no tools being required to disassemble or put it back together again. A single spring performed all recoil operation.

The main point of improvement emphasized by the inventor and one that, according to witnesses of the demonstrations, was practically useless was the unique method of getting the gas pressure from the barrel without tapping it, as was customarily done by all weapons that operated by the forces of the still expanding gas.

This device functioned as follows: When the projectile passed through the flared-out portion at the muzzle, the gases entered a trombone-shaped nozzle and exerted considerable pressure on the gas piston which was thrust evenly to the rear, unlocking the bolt from the barrel and shoving it to its full recoil position.

Lauf's only new feature was to entrap at the muzzle end the gas that was shoving the bullet through the bore. It was then used to operate his mechanism in the manner employed by numerous other actions powered by the forces of expanding gas. He was forced to use an unusually short barrel in order to have high enough residual pressure to operate the mechanism after waiting for the projectile to clear the muzzle.

The safety located at the rear of the pistol grip handle was the squeeze type commonly found on automatic pistols.

While the German Army was not even mildly interested in this peculiar gun, it did get desperate enough for automatic weapons during

Knorr-Bremse Machine Gun, Model 35/36, 7.92 mm.

World War II to manufacture a limited number for its ally, Finland, which reportedly had also bought the few that were made up by the Swedish Government. All known models were chambered for the 7.92-mm German infantry rifle cartridge.

The Knorr-Bremse company also had under construction an automatic 20-mm cannon built on the Hans Lauf principle but like the others it did not get much beyond the prototype, or limited use, stage.

To fire the L. H. 33, or the Knorr-Bremse 35/36, the gunner from a prone position inserts a loaded 25-round clip in the left side of the feedway. The retracting handle is then pulled back until the gas piston extension is engaged by the rear sear. The pistol grip is grasped by the right hand to depress the safety and, if automatic fire is desired, the center pivoting trigger is pulled back at the bottom. The bolt connected to the piston extension flies forward under tension from the driving spring, thus stripping the first cartridge from the mouth of the magazine and chambering it.

At the moment of going into battery, the rear of the bolt arrives directly over a recess in the stationary receiver. This permits the piston extension in continuing forward to actuate a linkage arrangement that forces the back of the bolt down into its locking recess. In doing so, it alines the firing pin in the bolt with the L-shaped end of the piston extension that on the final forward movement smashes into the protruding firing pin which in turn detonates and fires the cartridge.

The bolt is securely locked to the receiver until the bullet is clear of the bore. The greatly reduced gas pressure is now diverted by means of a large trombone-shaped pipe that, by use of its reduced force, evenly thrusts the gas piston rearward. Its first movement breaks the link and the end of the bolt is then lifted up out of engagement with its locking recess. It starts to recoil as the extractor first pulls the empty cartridge from the chamber and then holds it until the ejector pivots the used case out through the slot cut in the right side of the receiver. At the end of its recoil movement under energy of the compressed driving spring, the action starts in counterrecoil movement to repeat the operation.

Chapter 31
Mauser Machine Guns

Background

Very few arms companies have been as influential in world affairs as the Waffenfabrik Mauser A. G. from the date of its inception in 1871 until the end of World War II. At its very beginning Mauser products were used by the German Government to disseminate German beliefs. The authorities of that country recognized that by arming soldiers and police of smaller countries, it could also influence greatly their military way of thinking.

The company was organized by and named for Paul Mauser, who devoted his life to the invention and development of all kinds of weapons in the interest of his fatherland. The youngest of 13 children, he was born on 27 June 1838 at Oberndorf, Germany. His father, Andreas Mauser, was himself a master gunsmith in the Government arms factory at Oberndorf. At 12 years of age, Paul was already an apprentice gunsmith. After completing his schooling, he and several of his brothers were well established as craftsmen in weapon construction.

Europe, as usual, was on the verge of a war and young Mauser was called up for military duty in 1859. At this time he so impressed his officers that he was immediately placed on inactive status and given a responsible position in the Royal Fire Arms Factory at Oberndorf, where he might turn his creative talents to good ends. It was here that he developed his famous bolt-action rifle that was to become the design pattern for practically every military power in the world. And here he organized the company that bears his name.

It is not generally known that the first patent to be applied for by Mauser on his rifle was sought from the United States Patent Office. The rifle was followed by numerous other inventions that included many types of semiautomatic actions. They were later to be copied and modified into full automatic mechanisms by arms designers in every corner of the world. These superb small arms, both bolt-action and semiautomatic, made the name Mauser synonymous with ordnance of exceptional quality. His conception and development of this type of armament brought him lame and fortune, and his government a chance to rise in military strength. Mauser died in 1914 as his country stood ready to challenge the power of the rest of the world.

After the war, the Allies occupied the country with a commission established in order to limit the ability of the German arms companies to produce for military use the many automatic weapons that had proved so deadly. The Mauser Co. continued in existence and it was hurt least of all by the occupation forces, since its factories turned out mainly rifles and semiautomatic pistols.

The large machine gun producing plant of Deutsche Waffen- und Munitions-Fabriken (D. W. M.), with which the Mauser Co. often contracted, was completely dismantled and the latter firm was allowed to acquire its patent assignments. Among them were the Luger pistol and the many improvements by Karl Heinemann on the Maxim machine gun, then known by the D. W. M. code name of Parabellum. The company was not permitted to manufacture the Parabellum because of the Versailles Treaty and therefore, in order to remain solvent, an output of sporting guns and general small arms was manufactured commercially until 1934 when Germany, under the Hitler regime, openly began to rearm.

The Nazi high command, realizing the potentialities of the great Mauser organization, started at once to recruit talent and make a loan necessary for maximum production. In this manner the Waffenfabrik Mauser A. G. was officially launched in an all-out race for arms supremacy.

MG-34

Its first effort was in the field of rifle caliber machine guns. A pressing need at that time was for a single machine gun using the 7.92-mm rifle cartridge, which would incorporate in it all the special features of modern weapons. It should be capable of use as both a light and heavy machine gun and, if need be, for antiaircraft work against low flying attack planes. The basic design for the weapon was sent to Mauser from Berlin and was the further development of a mechanism patented by Louis Stange, an engineer of Rheinmetall-Borsig. The specifications further stated the weapon must feed from both left and right and be fed by either drum or belt.

The weapon conceived by the officials in Berlin was the last word in machine gun design and eliminated the locking ring. In lieu of this system they recommended a rotating bolt head, the origin of which has been credited to Paul Mauser, Ferdinand Mannlicher, and even Alfredo Scotti. True, Mauser, at a much earlier date, successfully used a bolt that locked in a somewhat similar manner but for energy after unlocking by recoil forces he resorted to the high residual pressure in the chamber to give him the needed power to complete the cycle of operation. Mannlicher and Scotti used a gas piston both to actuate and unlock the operating mechanism. Stange's method, applied to the new weapon, differed inasmuch as it unlocked by recoil and used barrel energy and an accelerator to speed the bolt action to the rear.

The bolt body was first accelerated when the unlocking cams were engaged. On release of the bolt head, the rear portion of the two-piece bolt traveling at a high speed pulled the front piece with it. A closely calculated distance for unlocking, which utilized the safe but very high chamber pressure then being exerted on the face of the bolt, further added to the rate of fire. The pressure and recoil forces were both abetted by the muzzle booster that fitted over the end of the barrel. The booster not only held the high gas pressure after the bullet had cleared, but made it do double work by bringing it to bear on the barrel face for additional rearward thrust of the recoiling parts.

The result of Mauser's development of this method of operation was called officially the MG-34. It represented not so much a departure from conventional design as it did the sensible application of many well-established principles in the design of this most efficient machine gun. For instance, the muzzle booster was so constructed that it served as a flash hider and front barrel bearing as well as a gas trap.

Few machine guns on first appearance showed as much refinement as did the MG-34. The German high command evidently was greatly impressed as it was adopted in short order. Although development was not begun until 1934, it was put into production in 1936. Its most

Mauser Machine Gun, Model 1934, 7.92 mm.

Mauser Machine Gun, Model 1934 S, 7.92 mm.

desirable feature was that, even with a high rate of fire, the straight-line action did not jar or impede the gunner's aim. The weapon was nearly as accurate as an infantry rifle when fired single shot.

The MG-34 soon became the standard machine gun of the German Army. It was mounted for light machine gun work with a bipod and for heavy duty with a tripod that could raise it to a high enough position to make it readily adaptable for antiaircraft use. A dual mount was also made at a later date whereby two weapons could be operated by a single soldier and, although designed for antiaircraft use, it could and often was employed by armored vehicles.

The MG-34 can be described as being an air-cooled, rear-seared, short-recoil-operated, belt-or drum-fed, dual-purpose light machine gun, chambered for the 7.92-mm rifle cartridge.

It normally employed a nondisintegrating push-out type metal link belt, which came packed in 50-round lengths. It was common practice in the field for the gunner's helper to clip as many as five such belts together. At the beginning of each one there protruded a small rectangular tongue, while the last link contained a matching hole. To join as many belts as needed, the tongue of one was merely passed through the hole in the last link of another until a small projection in the tongue snapped into place, joining the whole assembly together. The belted round then made it impossible for the links to separate until the cartridge was removed. In certain field operations necessitating rapid movement, a 50-shot drum was often employed. The magazine fitted against the left side of the receiver and was loaded with a single 50-round belt.

To insure against firing out of battery, a mechanical device, located on the right side of the breech lock, serves as an obstruction to the cocked firing pin. It can be removed only by a short sloping face beneath the front end of the bolt carrier camming it down after the barrel and bolt are locked together. To avoid rebound of the bolt assembly, a spring-loaded catch is fastened at the rear end of the barrel extension in the path of the outer roller on the bolt head. The piece is depressed during locking operations and rises again when the roller passes over it, thus serving as a sort of flexible chock. After the first three-sixteenths inch backward travel of the barrel and bolt, the roller is forced over the catch and only then is the bolt free to unlock.

Another safety that prevents accidental discharge is located in the receiver immediately above the trigger. A relief is cut in it that permits movement of the sear when the lever is in Fire position. The sear release is shaped like a pivoting lever and, on Safe, it pins the front end of the trigger bar, thereby preventing it from actuating the sear.

The firing pin, housed in the bolt body, is cocked during; the recoil movement. It is nested inside its spring under constant slight tension. Full compression on its rearward travel is reached by means of two cam shoulders at the rear end of the bolt head bearing against corresponding shoulders at the front end of the bolt carrier. During the partial rotation movement brought about by unlocking, the carrier is cammed back and the firing-pin spring compressed. At this point the sear engages the notch in the firing pin holding it back and is released by the revolution of the bolt head after the bolt is locked to the barrel. This removes a safety obstruction and at the same time lifts the end of the firing-pin catch, allowing it to be driven forward.

Upon pulling back on the top portion of the trigger, for single fire, the rear end of the lever mounted on the trigger depresses the sear that allows the bolt to go forward. The projection on the bottom of the bolt pushes down a short upper arm of the sear-lever trip; this frees the sear-lever bar to go forward and the sear to rise; thereupon, with the return of the bolt on its recoil stroke, the sear is forced into its recess in the bolt holding it in the cocked position.

When the bottom part of the trigger is pulled, for automatic fire, the sear is depressed and the bolt driven towards battery. Housed in the main body of the trigger is a small auxiliary trigger. Upon being retracted, its projecting lug at the rear is raised above the trigger guide pin, thus permitting further rearward travel of the larger trigger than when firing single shots. Consequently, it is not possible to aline the sear with its recess in the bolt and automatic fire results.

The mechanical means by which the push-out type link belt is fed into the gun is housed in the cover group and has a pivoting arm the ribs of which form a groove into which rides a stud located on top of the bolt. A holding pawl under spring tension is mounted in the feed slide and positions itself behind each cartridge with every throw of the slide. Heavy spring-loaded guides press each successive round down into alignment for chambering, with the full indexing movement of the cartridge belt.

When mounting the drum magazine, the feed block must first be removed. The cover group is provided with an opening that is closed from the weather by hinged flaps when the drum is not in use beneath the ejection slot a dust cover (for the protection of operating parts) automatically opens when the trigger is pressed.

The ejector has no spring in its construction, being in the form of a pin housed in the head of the bolt. It has a cut-away portion for its retainer that allows it a longitudinal travel of only three-sixteenths inch. During recoil, when the empty case has been withdrawn the necessary distance, the pin contacts a case-hardened stop on the right side of the receiver body. The empty cartridge is struck by the pin at the top of its base, pivoting and at the same time knocking it down through the ejection slot in the bottom of the receiver.

The weapon was later altered for use in armored vehicles and differed from the parent gun by having a heavier barrel jacket to adapt it to a ball-type mount. It was known as the MG-34 (modified) and was followed by the MG-34-S and MG-34-41, identical in appearance except for the barrel jackets but marked as distinct models. They differed from the original MG-34 in the following points: (1) Full automatic fire only; (2) shorter barrel; (3) a trigger group of simpler construction; (4) a larger buffer; (5) larger muzzles on the barrels to add more surface for booster gas to bear upon; (6) elimination of the firing-pin nut; and (7) minor changes in the feed system.

To fire practically any of the MG-34 machine guns, the operator, if using a drum feed, presses a catch on the drum to slide back the cover. The end of the cartridge belt is pulled out and inserted in the left side of the feedway. The drum is attached to the forward part of the receiver guides, front end first, and the rear pivoted around to the lugs in the feed block. The end of the belt is then pulled to the right until the first round is engaged by the three pawls on the underside of the feed cover. The gun is charged by pulling the cocking handle smartly to the rear as far as it will go, then shoving it forward until the holding detent snaps into its locking recess. The catch on the safety lever is depressed to firing position until the letter F (Fire) is uncovered.

Comparison of Component Parts of the Mauser Machine Guns of the MG-34 Series.
(A) MG-34. (B) MG-34 (Modified). (C) MG-34 S (D) MG-34/41.

For automatic firing, the bottom part of the trigger is pulled to the rear. This releases the sear and the bolt, which has been held in the cocked position, flies forward from the energy of the compressed driving spring. A feed piece on top of the bolt, being spring loaded, rises and strikes the base of the indexed cartridge, pushing it out of its linked position for chambering. Continuing on, the feed arm, actuated by the projection on the top rear end of the bolt carrier, causes the carrier to move the cartridge belt over a half space.

At the same time, the two inner rollers on the bolt head engage the cams on the barrel sleeve, causing a partial rotation of the bolt head clockwise so that the bolt buttress threads engage those on the cam sleeve and lock the bolt to the barrel. This movement also forces the extractor lip over the rim of the chambered round. The bolt carrier can now continue forward just enough to allow the firing pin to be driven into the primer.

The counterrecoil stroke is stopped completely as the shoulder on the bolt carrier's right front strikes the cocking-handle stop. The bolt-locking catch has now lifted behind the outer roller on the bolt head, and the exploding powder charge starts recoil movement with barrel and bolt locked together for three-sixteenths inch of rearward travel. The bullet has now cleared the bore but a high residual pressure still remains in the chamber.

The rate-of-fire booster traps the muzzle blast which reacts with great force on the face of the barrel adding considerable thrust to the recoil. After three-sixteenths inch free travel, the outer rollers on the bolt head contact the two cam faces in front of the barrel extension and the bolt head makes a quarter turn counter-clockwise, thus unlocking the bolt from the barrel. Recoil movement of the barrel is then stopped as its cam sleeve butts against the shoulders in the front end of the receiver. The feed arm stud moves the feed pawl until it slips over the first round in the belt.

As the bolt continues to the rear, the empty cartridge case is held by the extractor claw. The latter had loosened the round by its initial

Comparison of Mauser Machine Guns of the MG-34 Series.
(A) MG-34. (B) MG-34 (Modified). (C) MG-34 S. (D) MG-34/41

rearward movement when the bolt head rotated to unlock, and now holds the base of the cartridge to the front of the bolt. The rear end of the ejector pin next strikes its stop, pushing it through the bolt face, pivoting and knocking the spent case through the ejection slot in the bottom of the receiver. The complete recoil stroke of the operating assembly is finally stopped by the buffer which absorbs the surplus energy and deflects it forward into counter-recoil movement to repeat the cycle.

The use of a rotating bolt head in place of the locking ring featured in earlier German machine guns has caused writers to credit the series of weapons that soon followed to other inventors. But, if Stange's patent granted in 1928 is checked closely, it will be disclosed that the roller locking arrangement will accelerate the rear portion of the two-piece bolt by recoiling barrel movement at the instant of unlocking. While earlier machine guns had locked and freed the bolt by turning the head of this part, they most certainly did not utilize speed of barrel recoil to accelerate its movement rearward.

It has been a moot question as to why the locking ring, successfully used by early ground guns, was suddenly dropped in favor of this system. The answer seems to be that the locking ring made barrel change, although fast, possible only with components that later had to be removed from the hot barrel and placed on the cool one. The rotary bolt allowed all operating parts to be retained in the receiver while the overheated barrel was quickly removed by itself. This feature alone justified the substitution.

The German field manual recommended that a barrel change should occur after 250 rounds had been fired continuously or with only short pauses between bursts. The following procedure was specified: The operator cocks the bolt to the rear after setting the selector lever on Safe. He depresses the receiver catch just below and back of the back-sight pivot and turns the receiver body 180° to the left. The muzzle is then raised

until the barrel drops out of the rear end of the jacket, after which it is lowered and a cool barrel dropped in. The receiver is turned to the right until the catches snap into the holding detents. The operator switches to Fire and grasps the cocking handle with his right hand. The trigger is pulled with the other hand and the bolt goes home slowly. The weapon is now ready to be cocked and firing resumed.

The following arms firms manufactured the MG-34: Mauser Werke and Maget, both of Berlin; Gustloff Co., of Suhl, Saxony; Steyr-Daimler-Puch A. G. of Vienna; and Waffenwerke Brunn A. G. of Czechoslovakia.

MG-81

In 1936 when the MG-34 was put into production for the ground troops, the German Air Force became interested in the weapon as an aircraft machine gun for flexible and fixed mounting. The rifle caliber gun then in use in German aircraft was the MG-15 manufactured by Rheinmetall. The MG-15 was slow and expensive to produce so the Mauser firm was directed to develop an aircraft weapon, using the 7.92-mm rifle cartridge, and incorporating the bolt action of the MG-34. The new design was accepted in 1938 and put into production by Mauser in 1939.

For flexible mounting where an operator was available to hand charge and fire the piece a pistol grip handle was used. A strong spring buffer, fastened to the rear and inside the receiver, was also added.

This weapon was designated the MG-81. A small cocking handle was located at the rear of the receiver. It had a very high rate of fire, officially listed as 1,000 to 1,200 rounds a minute. A muzzle booster with a small orifice and an abnormally strong buffer spring was responsible for the increase over the MG-34, which was closely copied in operating action. No provision was made for firing single shots.

A very odd thing about the design of the gun was that its muzzle booster had no flash-hiding device attached to the end, as did all the other German machine guns of this type, whether for aircraft or ground use. Since it was produced for flexible mounting where it would be manually trained and fired, it was mystifying that this extremely high-speed short-barrel gun did not employ the conventional cone-shaped flash hider.

Feeding was done by means of a flexible disintegrating metal link belt rather than the saddle drum magazine used on its predecessor. The ammunition box could be attached to the side of the receiver, if desired, and permitted bursts of longer duration than did the drum arrangement. Power-driven turrets were being introduced at

Mauser Aircraft Machine Gun, Model 81, 7.92 mm, Dual Mount.

about the time this weapon made its appearance and resulted in making the observer and his free gun practically a thing of the past. In view also of its small caliber the weapon was destined to occupy a very minor position in World War II.

The MG-81, however, was the first aircraft machine gun to be installed by the Germans in twin mountings. It was so mounted in the Bola 81Z, and a few were later placed singly in the JU-88-A4, FW-189, and ME-110.

The weapon was manufactured for the German Luftwaffe by the following firms: Mauser Werke A. G., Oberndorf, which fabricated 46,000; Norddeutsche Machinefabrik G. m. b. H., Wittenberg; I. C. Wagner, Muhlhausen; Heinrich Krieghoff Waffenfabrik, Suhl; and L. O. Dietrich, Altenburg. Waffenfabrik Brun A. G. also produced the MG-34, in addition to the ZB weapons, following the German occupation of Czechoslovakia.

Chapter 32
Johnson Light Machine Gun

Melvin M. Johnson, Jr., is one of America's gifted gun designers. Born in Boston in 1909, he is a graduate of Harvard University and Harvard Law School. In 1933 he was commissioned in the Marine Corps Reserve and became captain in 1938. As early as 1937 Johnson produced experimentally a prototype light machine gun chambered for the caliber .30/06 United States infantry rifle cartridge. Empty, it weighed only 12½ pounds and was capable of delivering a maximum rate of fire of 500 shots a minute. The weapon had many good features, but the American Government viewed it with the customary caution it displayed toward progressive ideas on automatic arms.

After his rough version of the machine gun, Johnson modified and redesigned it in the years that followed. About 1 July 1940 he completed his first model of the Johnson light machine gun. It had a horizontal feed, and fired from an open bolt on automatic and from a closed one on semi-automatic.

In 1941 the light machine gun was tested by the Marine Corps at Quantico, Va., including a parachute jump from 400 feet. Packed in a pouch, the gun was assembled and fired within 90 seconds from the time of the jump.

The Marine Corps Equipment Board recommended its adoption for issue to parachute troopers and raiders. It was used in limited quantities with considerable success by Marine units in the Pacific and by the Army's First Special Service Force in the Italian campaign and landings in southern France: The annals of the latter group state that "pound for pound it was the most valuable armament the Force possessed." About 5000 Johnson light machine guns in all were produced by the manufacturer, Johnson Automatics, Inc., Boston, Mass., at a plant in Providence, R. I.

In August 1942, after seven months of war, the United States Army Ordnance Department bought five Johnsons for test and experimental firing. It was reported, after examining the weapons, that "while called light machine guns by the manufacturer, they are not considered such by the War Department since they do not use belts but are fed from 20-round magazines." This official decision seems odd since the Browning Automatic Rifle was fed in the identical manner with the same number of rounds.

The five weapons, after a visual inspection, were shipped to Aberdeen Proving Ground for check firing. There it was discovered that the safety lever was defective and the group was promptly sent back to the manufacturer for correction. Upon being returned to the Proving Ground in September 1942, a total of 50 rounds was fired from each of the five. Then all were shipped to the Infantry Board to fulfill a request from that organization to see them.

No further government testing was done until December 1943 when the Johnson firm offered an improved model to the Ordnance Department. Incorporated in its construction were many things found more desirable as a result of over two years of combat use. The new version, known as the Model 1944, had only 11 parts and could be field stripped in less than 20 seconds and reassembled in 30 seconds. The method of operation was unchanged, short recoil with unlocking timed to coincide with a high but safe operating gas pressure.

The 1944 model differed from earlier designs in that it had a folding monopod mount and a slight improvement in barrel change. A field cleaning kit was placed in the butt stock of the gun. In some experiments at the factory a muzzle booster was used to accelerate the recoil forces for a higher rate of fire. This did hasten the cycle of operation but resulted in considerable breakage. For an infantry weapon its rapidity of fire had always been considered as high as needed and the muzzle attachment was dropped.

Melvin M. Johnson, Jr., Firing the Weapon He Designed.

In automatic firing, rotation of the bolt tripped the sear releasing the spring-loaded firing pin. For semiautomatic discharge, the trigger had to be pulled with each shot. The Aberdeen report of this model stated: "Test results were generally very satisfactory under normal conditions, but unsatisfactory under adverse conditions of mud, cold and dust."

Again the weapon was returned to the factory and in March 1944 its performance showed considerable improvement under adverse conditions. It fired successfully during the standard rain test for 200 rounds, but became more difficult to operate as the trial progressed, finally becoming inoperative after the 383rd round.

It failed to fire full or semiautomatic after the dust test with either a clean or dusted magazine. When the weapon had been liberally oiled, a dusted magazine was fired without difficulty. Also 100 cartridges were fired without interruption after 17 hours in a cold room at a temperature of 40 degrees below zero Fahrenheit.

The Marine Corps Equipment Board had been testing similar guns at Quantico, Virginia, and this board recommended that the Johnson light machine gun be adopted in place of the Browning Automatic Rifle. The suggestion was not followed for the reasons stated below:

"(1) The swift tempo of Marine Corps operations with subsequent limitations on training time available. (2) The fact that the Marine Corps considers itself to be a customer of the Ordnance Department in small arms matters, and consequently, is reluctant to adopt an automatic shoulder weapon which is not an Army standard."

The same letter from the Commandant of Marines provided support and recognition of the inventor's contribution:

"The Marine Corps desires to lend impetus to the continual development of the Johnson light machine gun, and stands ready to perform such functions in that connection as may be considered desirable."

The Ordnance Department at a later date (May 1945) reviewed all the information available and decided to purchase 10 guns and accessories which were delivered and distributed as follows: Infantry Board, 3; Marine Corps, 2; Aberdeen Proving Ground, 2; Headquarters, Army Ground Force, 1; and Small Arms Development Division, 2. All spare parts were sent to the Aberdeen Proving Ground.

A final report on the Johnson weapon was made in October 1945, three months after the end of the war. No definite conclusion was cited, but it was intimated that it would be desirable to convert it to a belt-fed machine gun and that research and development were continuing.

Undoubtedly the Johnson light machine gun was an excellent weapon with many attractive and novel features, many of which were quickly copied by the enemy.

The selector switch is located on the right side back of the top part of the trigger. For semiautomatic fire the change lever is rotated into the forward position. If the cocking handle is pulled back to the rear and released, it will chamber the round and lock the bolt ready for single shots

Johnson Light Machine Gun, Model 1941, Cal. .30/06.

at each trigger movement. When the automatic-fire position is used, the bolt will remain retracted at the end of each burst, allowing air to circulate through the open bore.

If, after firing a short burst, it is found desirable to recharge the magazine, it may be done by inserting the five-round clips through the loading aperture on the right side of the receiver, regardless of whether the bolt is open or closed. In semiautomatic fire a full magazine can be kept available for an emergency that would call for an extended burst. Loading in this manner is not normally intended for automatic fire, as replacing the magazine with a fresh one is but a matter of seconds.

One of the most desirable features on this light machine gun is the gunner's ability to fire semiautomatic with a closed bolt merely by changing the selector switch with finger pressure. Thus shooting was as accurate as with any similarly constructed rifle. Lurching forward off the rear sear, an act that disturbs aim in all guns employing the rear sear for inertia firing, is thus eliminated in this method of single-shot firing.

It would seem impossible to make a quicker system of barrel change. On the 1944 model with the bolt at the rear, the point of a bullet is inserted in the latch and shoved forward. This releases the holding catch and forces the barrel forward due to the action of the barrel return spring. The barrel, if hot, may then be shaken all the way out, or withdrawn if it can be handled. To assemble, the cool barrel is shoved down as far as it will go. Upon being seated, the locking latch will be cammed into place holding it secure. During demonstrations a complete barrel change has been done in six seconds.

To fire the Johnson light machine gun, a loaded clip is inserted in the left portion of the receiver until the holding catches click into engagement. If automatic fire is desired, the selector switch is set and the cocking handle pulled all the way back or until the rear sear engages its notch in the bolt. When the trigger is pulled, the connecting sear is released from the bolt, allowing it to be thrust forward by compression of the driving spring in the butt stock.

After pushing the cartridge out of the magazine, the bolt chambers it as the extractor cams its claw over the rim. Just below final forward movement is halted, the locking cam on the rear of the bolt rotates the latter piece. It is fully secured as the action goes through a 20-degree arc, engaging all eight of the locking lugs. This last movement also releases the firing pin which flies forward, detonating the primer.

When the cartridge is fired, the barrel, its extension and bolt locked together recoil for a full one-eighth inch at which point the angled face of the operating cam contacts its corresponding face in the receiver body. This causes the bolt to rotate until the piece is free to recoil. This act is timed to coincide with a high residual pressure in the bore which adds to the speed of the bolt. The barrel, traveling only seven-sixteenths of an inch rearward, is brought back to battery by its return spring.

The locking angle on the lugs permits sufficient creep during the act of unlocking. The

Johnson Light Machine Gun, Model 1941, Disassembled. For Paratroop Work.

empty cartridge is jacked hack and freed in the chamber so that the extractor has only to hold it in position for ejecting. This is done when the ejector strikes the base of the round and kicks it out the right side of the receiver. The bolt continues to go to the rear until stopped by the compression of the driving spring.

All operational parts are then put in counterrecoil. As the bolt passes the rear of the magazine mouth, its face pushes the next cartridge out of the lips of the feed system and starts to chamber it. As long as the trigger is held to the rear, the cycle will continue.

In addition to his light machine gun, Melvin Johnson developed and produced a highly regarded semi-automatic rifle, some 50,000 of which were made and delivered during the war to various Allied forces. He also originated, at the request of the Navy Department, a 20-mm aircraft cannon.

Chapter 33
MG-42 Machine Gun

In 1942 the Germans, after nearly 3 years of war, introduced into their services a machine gun known as the MG-42. It represented during World War II one of the finest machine guns manufactured for effort and money expended. The Germans, using the already highly successful MG-34 as a guide for such factors as length, weight, ballistics, and rate of fire, attempted to solve for the duration of the war their army's light machine gun problems. Only the soundest and most proved features known to them were put into its construction.

It was a weapon of devisement, contributed to by many, rather than the single invention of any individual. For instance, the barrel change was an improvement over the Italian Breda, and the locking was an adaptation of the patented locking arrangement of Edward Stecke, a citizen of Warsaw, Poland. It is believed by many that, with the overrunning of Poland in 1939, one of the things seized by the Germans was a mock-up of a machine gun having Stecke's locking action. Realizing that it had many advantages, they added it to the list of fine features to be incorporated in a single ideal machine gun.

After the mechanism was finally decided upon. Dr. Grunow, a German industrialist, whose specialty was mass production by metal stampings,

Machine Gun, Model 42, 7.92 mm.

was ordered to devote his talents toward manufacture of the weapon without employing complicated methods or equipment. Dr. Grunow's accomplishment of this task by extensive use of pressing, riveting, and spot welding was a thing that will be studied and closely copied in machine gun construction for years to come. While its finished appearance was by no means as striking as that of other German machine guns, its battle life and performance was even greater than the normally high German standards for such arms.

The need for frequent barrel change because of the unusually fast rate of fire was met by the introduction of a most novel and efficient method for accomplishing it. A barrel throw-out lever was hinged on the right side of the receiver. It could be swung out bringing with it the hot barrel, which was supported by a metal loop attached to the inside of the actuating lever. The barrel could then be pivoted out of the rear of the barrel jacket and dropped without handling.

Feeding was done by a continuous metal belt through the feed block. Two feed pawls were linked to the front end of the arm by an intermediate link in such a way that when one was chambered, the other was being positioned behind the next round in the belt. Loading was thus performed in two stages instead of one continuous movement. This made lurching of the belt less violent and did not impede the gunner's aim.

The Germans, being perfectly satisfied with its ballistics, adapted the MG-42 to take the 7.92-mm infantry rifle cartridge. Although it did not weigh much more than an ordinary military rifle, no provision was made whereby it could be fired single shot, the only two settings on its selector switch being for Safe and for Automatic fire.

The system of operation was short recoil. Free travel of locked bolt and barrel was allowed for a short distance. The bolt was then unlocked and the high chamber pressure being held by the muzzle booster exerted itself on the barrel face and through the bore to the now empty cartridge, thus giving an abnormal rate of fire for such a light firing mechanism. Its cyclic rate, when using special ammunition, was asserted to be 1,350 rounds a minute and the normal number of rounds per minute with standard ammunition was 1,200 shots. While this may seem unnecessarily high for an infantry weapon, its importance for fire power effect was obvious.

In lieu of the rotating bolt head, successfully used on earlier machine guns of this type, locking of the bolt to the barrel was achieved by means of a wedge situated in the bolt head. This wedge was formed by two locking pieces, each being a small two-dimensional roller arranged symmetrically in slots in the sides of the bolt head with their axles vertical. The rims of the circular locking pieces were forced outwards so that the axles which projected above and below the slots engaged corresponding grooves in the barrel extension. On recoil the locking parts were forced in by stationary ramps and the light bolt was free to move to the rear under the action imparted by the gases from high chamber pressure exerted on the bolt face by the spent cartridge case.

The MG-42 was used with a bipod as a light machine gun, and on a tripod as a substitute for the heavier type. The barrel-jacket cover and feed parts and receiver were constructed of stamped lightweight sheet steel welded lengthwise. The bolt's slideways were welded inside the receiver. The shoulder piece was made of plastic. On the right side of the barrel jacket a long slot purposely was left open so that the barrel could more easily be removed. Manipulation of the lever in the receiver on this side would force the rear of the hot barrel out and allow it to slide untouched to the ground.

As an example of the thoroughness of design whereby each component or accessory performed as many functions as possible, the muzzle booster is perhaps outstanding. This simple device, fastened to the forward end of the barrel jacket, not only trapped the still expanding gases after the bullet left the bore, but it also served as a front barrel bearing and flash suppressor. It was so slotted that the escaping gas, after it had been reworked, hit against angled buffers to serve as a muzzle brake for stabilizing the weapon during a short burst at an abnormally high cyclic rate.

The Germans, in developing and producing the MG-42, abandoned all former rules and regulations on both production and finishing of material. This led to the erroneous belief that

Components of the Machine Gun, Model 42.

a desperate shortage of certain materials existed in Germany and that automatic weapons of inferior quality were being made, since externally they did not meet the erstwhile meticulous German standards. The truth of the matter was they simply had mastered the art of producing fine automatic weapons with no more expense and time than would be needed to make a dozen cap pistols.

About the only real weakness was its variety of tactical uses, in line with a typical German characteristic. Once a fine weapon has been in production, invariably an attempt was made to adapt it to every conceivable use from anti-aircraft in batteries to individual-burst fire by the infantryman. Its employment by the latter incidentally was its most effective. And while many have pointed out that its terrifically high rate of fire for infantry use would make the muzzle climb if a long burst were tried, it must be remembered that the weapon was ordinarily only fired for a fraction of a second during each burst. Since it was being discharged at a rate of 22 shots a second, the striking bullets could be held to a small enough area to cover it thoroughly. It acted more in the capacity of a long-range shot gun than as a machine gun. The German Army considered the MG-42 one of the most excellent weapons known not only for inflicting heavy casualties on infantry in movement but doubly so for its effectiveness in keeping the enemy pinned down when dug in.

Ammunition was fed to the weapon by flexible metal belts, each holding 50 rounds, that could easily be spliced to any length desired. A drum magazine, also holding one 50-round belt, could be attached to the left side and a few have been known to be modified to take a saddle drum feed that held 75 belted cartridges.

In loading the MG-42, the feed cover can be either open or closed, so long as the first round is positioned at the cartridge stop. The spring-loaded cover for keeping dirt out of the ejection slot flies open the instant the trigger is pulled

back. When firing has been interrupted for any length of time, this piece is snapped shut by hand. It is one of the easiest known machine guns to unload. The selector is simply switched to Safe and, after unlatching, the feed cover is raised as far as it will go. The remainder of the belted ammunition can then be lifted out.

The bolt is removed first by letting it go home, then by twisting the butt stock to detach the latter. The driving spring and bolt then slide readily out the rear. The barrel has a relatively short but heavy barrel extension which is screwed to its aft end.

To fire the MG-42, the operator, generally from the prone position, puts the tab end of the cartridge belt through from the left side of the feedway and pulls to the right until the first cartridge comes to rest against its stop. With the weapon set at Safe, the charging handle on the right side of the gun is pulled all the way to the rear. The searing device will then engage its locking notch in the bottom of the bolt. The selector switch is turned to Fire and the trigger pulled.

As the bolt is thrust forward by the compressed driving spring, the bolt face knocks the cartridge out of its link ahead of the counterrecoiling parts into the chamber. As the movement continues, a locking stud on each side and at the front of the bolt starts to engage a corresponding cam in the barrel extension. By forcing the lugs into their locking recesses, the bolt face is brought securely behind the base of the already chambered cartridge. Final movement cams the extractor lip over the rim and into the cannelure of the round. At the same time, the firing pin, which is trow an integral part of the rear portion of the bolt, is driven forward by inertia and detonates the primer to explode the powder charge.

While the powder gases are reaching peak pressures and the bullet is still in the bore, the bolt is held securely to the barrel, both pieces traveling rearwards as a unit until a distance of one half inch is reached. Then travel of the barrel and its extension is stopped. At the same time the pins in the locking head are cammed out by contact with the unlocking ramps, withdrawing them from their seats. The bolt is thus freed to continue to the rear, accelerated by the impact of the high residual pressure in the bore on the face of the bolt, while the barrel-return spring pushes the barrel and extension back to battery.

The cartridge case loosened by the first act of unlocking is carried to the rear by the extractor and is held until the ejector knocks it through the opening in the bottom of the receiver. The first movement of the bolt in recoil levers the next round in the belt into position and places the feed pawl behind the next cartridge as the bolt continues to go rearwards until it strikes the strong helical spring located in the shoulder stock. Deflection, working in conjunction with the stored energy of the driving spring, starts the operating parts back into counterrecoil to repeat the cycle of operation.

When placed in use as a heavy machine gun, it was found necessary to provide a specially constructed muzzle brake for the MG-42. The device counteracted the tendency of the muzzle to jump when a burst of long duration was fired. This followed the unsuccessful trials of a standard booster. The first use of the specially designed muzzle brake was late in 1943 and it was continued effectively until the war's end. The brake, which was attached to the flash eliminator and gas-pressure trap, had two baffle plates and was made to give more braking effect and lower cyclic rate than did the standard one.

The following arms plants manufactured the MG-42 for the German Army: The Johannus Grossfuss Metall- und Locierwarenfabrik, Dobeln, Saxony (Dr. Grunow was on its staff); Mauser Werke, Berlin; Maget, Berlin; Gustloff Co., Suhl Gun Works, Suhl, Germany; and Steyr-Daimler Puch A. G., Vienna, Austria.

After the United States entered the war against Germany, the Ordnance Department sought to copy a captured German MG-42. The Saginaw Steering Gear Division of General Motors was given the assignment. Drawings were completed in June 1943 and the first guns produced were test fired on 1 October 1943. Serious malfunctions were found to result and the components were then reworked. When it was thought to be ready, it was again put on trial in February 1944. The results were so discouraging that the discharge of a hundred rounds had to be done in bursts of two and three shots. Again the parts were modified and "beefed up" until it

Machine Gun, Model 42, 7.92 mm.
View Shows Cover Open and Barrel Release Latch Open with Barrel Partly Removed.

was thought to be capable of the basic 10,000-round endurance test required by the Army before being considered even for limited use. After 1,483 rounds had been expanded, the test was stopped, there having been over 50 serious stoppages.

An intensive study was ordered on the failure of American engineers to copy successfully this German machine gun which had been stamped out of the most ordinary of materials. The investigation revealed that inadequate compensation for the difference between the cartridge length of our caliber .30 M2 and the German 7.92-mm cartridge case had been made and that the receiver on the American version was too long. The rear lugs on the bolt body also had not been placed far enough back to allow the bolt face to recoil behind the ejection slot in the bottom of the receiver. As a result the receiver yoke interfered with the cartridge guide plate by as much as a quarter of an inch.

It was concluded that extensive redesign would be necessary to correct these serious defects in both receiver and bolt mechanisms and further expenditures or developments were ordered stopped. Two models of this American-made failure, known officially as Machine Gun Cal. .30T24, were shipped to the Springfield Armory and placed in its museum for reference and historical purposes.

Chapter 34
FG-42 Machine Gun

German military and industrial leaders, believing they had taken care of infantry armament needs, next turned their attention to a machine gun on which consideration had to be given to balance and lightness of weight. This weapon, manufactured by Heinrich Krieghoff Waffenfabrik, Suhl, Saxony, was intended for air-borne soldiers, a mode of warfare so far untried. With the invasion of Crete by air the Germans introduced the new paratroop machine gun, called the FG-42. It was promptly confused with the MG-42 by observers reporting the incident. The designation given the air-borne weapon represented the initials for Fallschirm Jaeger Gewehr (paratroop machine gun).

The gas-operated, air-cooled, bipod-supported weapon had a large ventilated fore-arm grip and an unusually light and short shoulder stock. It weighed only 14 pounds with bipod and a loaded clip magazine that held 20 rounds. The

Machine Gun, Model FG-42, 7.92 mm.

Section Drawing of the Machine Gun FG-42, Showing the Action Immediately After Firing.
Gas from the Barrel Is Acting on the Piston Which Will Rotate and Unlock the Bolt.

receiver body, which contained the slideway for operating parts, was stamped out of sheet metal. The fixed barrel was permanently fastened both fore and aft by having the receiver swaged circumferentially in a recess around each end and then further secured by the locking pin. A projection on the left side opened to permit insertion of a fresh loaded magazine when all cartridges were expended from the previous one. When not in use, it was closed by two metal spring-loaded flaps which flew open when their latch was shoved forward.

A combination flash suppressor and muzzle brake was screwed on the muzzle end of the barrel, being held in place by a spring latch attached to the front sight. This device absorbed a high percentage of the recoil forces. A gas cylinder beneath the barrel was held in place by a locking nut. An orifice selector permitted the gunner to regulate the amount of gas going into the cylinder from the port in the barrel, center punch marks showing him in advance whether the movement would position a large or small orifice.

The gas cylinder had four equidistant ports located far enough away from the forward end to permit the piston rod to unlock before uncovering the ports. It then discharged the expanding powder gases at the end of its rear stroke and took in air on the return movement. The gas piston consisted of a tube closed on the forward end. Its rear portion had a recess machined in its upper side in which a rear-searing device engaged. Two D-shaped holes were machined at its middle to contain a cocking handle. The driving spring, held in place by a guide, was inserted into and housed by the gas piston. A rather strong spring-recoil buffer at the rear of the receiver, just aft of the gas piston, was designed to stop the latter on completion of its recoil stroke. The rear-inserted bolt assembly operated in a slideway in the receiver, while a cartridge guide stamped in the receiver, held the cartridge in alignment for chambering.

The two halves of the sheet-metal trigger mechanism were welded together. This unit housed the sear, selector switch, and safety latch. A sear protruding through the receiver acted against the underside of the gas piston and permitted the gunner freedom to fire either single

shot or full automatic. The short wooden stock was held in place by a spring-loaded catch and could be readily removed by depressing the locking latch located at the right rear.

The Germans, being on the receiving end of the very efficient Lewis gun during World War I, developed a great respect for this fine and reliable mechanism. It is natural that, when possible, many experiments were conducted in order to incorporate any single feature or the whole basic action for their own advantage. The FG-42 was the result. However it was so highly refined and modified to meet special needs that it was hardly recognizable. The most unusual feature was the cleverly designed triggering mechanism that enabled the operator by a turn of the selector switch to fire full automatic or single shot. At the same time it gave the gunner the privilege of firing with either a closed bolt for accuracy when used single shot, or of leaving the bolt in the open position for cooling purposes at the completion of a burst of full automatic fire.

This weapon represented the highest degree of refinement the Lewis type of automatic firing mechanism had ever attained and was well designed for its intended purpose.

To fire the FG-42 full automatic, a loaded 20-shot magazine is inserted after the spring-loaded flaps over the feedway are opened by releasing the catch. The safety lever, locked in the up position, is pushed down and the selector switch swung forward to Full automatic. The cocking handle, grasped on the right side, is pulled smartly to the rear until the gas piston and bolt are held there as the rear sear engages its locking notch beneath the piston. The weapon is now cocked and a cartridge is positioned for firing.

When the trigger is pulled, the driving spring thrusts the bolt and piston forward. The face of the bolt engages the base of the first cartridge in the mouth of the magazine. As the round is forced forward, it leaves the magazine and is directed by the cartridge guide for alignment with the oncoming bolt and chamber. As the bolt reaches the end of its forward motion, the extractor lip snaps over the cartridge rim and the bolt face seats against the breech end of the barrel. The locking recesses are in position with the lugs on the bolt. However, the piston can still continue to travel and, in its attempt to do so, the beveled projection riding in the curved slot in the bolt body causes the bolt to rotate the lugs in their recesses and lock the piece. This act removes the obstruction that has been holding the action rearward. The added free travel permits the gas piston to drive the firing pin through the bolt face into the primer which in turn fires the powder charge.

The bolt remains securely locked supporting the cartridge while the bullet is in the bore. However, when it has passed the gas orifice, a portion of the expanding gases is let into the gas cylinder through one of the four regulating orifices. Pressure is exerted on the gas piston which starts to move rearward, carrying with it the firing pin held by the yokelike section on the rear part of the piston. The bullet is now clear of the muzzle and the yoke, after having had a free travel inside the bolt for over an inch, starts to act against the cam causing the bolt to rotate and become disengaged from the barrel extension.

When unlocking is complete, the bolt is free to be speeded back by the high residual pressure in the chamber. As it continues rearward, the empty cartridge case is withdrawn by the extractor and its rim brought into contact with the ejector operating through a slot in the bolt body. The empty case pivots about its extractor and is knocked through the ejection slot in the right side of the receiver, where it is deflected forward by a curved piece that is fastened rigidly to the outside of the receiver for this purpose. Additional movement rearward during the recoil stroke compresses the driving spring. The remainder of the energy of the operational parts is absorbed by their striking the heavy spring buffer. The latter, assisted by the driving spring, deflects the action forward to repeat the cycle of operation.