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The Berthier automatic rifle was a light machine gun prototype. The weapon could be converted from an automatic rifle to an LMG.
Development
The French Army, from the earliest days of automatic arms, has considered gas operation as the most logical method of deriving the necessary forces to actuate the firing mechanism. As was customary at the time, practically every young officer showing any aptitude in advanced weapon design was given a chance to carry out his ideas. Most notable of these was Lt. André Virgile Paul Marie Berthier, who, feeling that the Hotchkiss heavy machine gun was adequate in its field, tried to make for the infantryman a lightweight machine gun that could be carried with the ease of a carbine and at the same time had the fire power of the heavier weapon.
As early as 1905 Berthier applied for a patent in Belgium while serving in Constantinople, Turkey. His first gun was simply a straight-pull rifle of the Mannlicher type. A gas cylinder with piston was installed on the right side of the receiver. It drove the bolt handle rearward by means of gas pressure being exerted on the face of the piston. The bolt and handle were returned by driving-spring compression. The weapon used a conventional magazine feed located underneath it. This model was known on the continent as the Berthier-Pacha. The latter name, also spelled "Pasha," was added as an honorary title granted by the Turkish Government in recognition of Berthier's contribution to ordnance.
Three years later he perfected another design that would fit the specifications demanded for an infantryman and still be rugged enough to stand the rigorous trials of the French proving grounds. The weapon, when it first appeared, was known as the Berthier Model 1908.
The rate of fire on this early Berthier was approximately 450 rounds per minute. It was first manufactured by the Anciens Etablissements Pieper at Herstal, Belgium, and a pamphlet published by the company not only gave its many features as an infantry arm but also pointed out its adaptability to cavalry tactics. Like all air-cooled machine rifles that were forced to use lightweight barrels, heating was the paramount problem. As a solution Berthier devised a system that permitted him to cool the barrel with water and still retain its low weight. The barrel was covered by a fairly close-fitting jacket made in two compartments. Using two small connecting rubber bags containing water, the gunner's assistant forced the liquid through the jacket from one container to another. This system was found to be adequate for up to 600 rounds of sustained fire. As a further remedy, the barrel and receiver were joined by an interrupted thread that allowed the barrel to be changed in a matter of seconds.
The Berthier weapon represented the lightest water-cooled rifle-caliber machine gun that had yet been developed. Why it did not more than fulfill the requirements of the infantryman is not known, as it most certainly was an advance over the alleged machine rifles that were making their appearance at the time. One cannot help but note the comparison between the operating mechanism of the weapon upon which Berthier based his patent claim in 1909 and the later Browning automatic rifle that has proved so reliable in United States military service. The gas-operated rotating bolt in Berthier's first design of 1905 was a system that time has also proved to be among the best. It is hard to conceive that the French Army, having in its possession the nuclei of two fine automatic rifles, could have veered so far away as to consider the Chauchat. Only one conclusion can be drawn, namely, that mass production, so necessary to win wars, could not be geared to produce this well-balanced but hard-to-manufacture weapon, whereas the Chauchat, although admittedly inferior, could be turned out in practically any plumbing shop.
During the years between the weapon's conception and World War I, there was only enough interest shown by the various governments to which it was demonstrated to keep it from being totally forgotten. Many countries made inquiries and experimented at odd times with this machine rifle. However, France, the home of the inventor, seemed to go to great lengths to ignore it.
In 1916 Berthier, who had risen to the rank of general in the French Army, came to the United States to develop the weapon further, more by refinement of components for the purpose of being mass-produced than anything else, as the operating principles remained the same. On its first official trial by the United States Army in May 1917 the gun did not meet requirements. On 29 June of the same year, the Marine Corps after a very comprehensive test, reported it suitable for its use. The Ordnance Board tested the weapon again shortly after the Marine Corps made its report and this later Army board concurred with the Marines, who had again conducted trials that resulted in another favorable report.
The Army then ordered, on 2 October 1917, the manufacture for issue of 5,000 of these guns chambered for our caliber .30/06 infantry cartridge, provided the order did not conflict with other machine rifle production that was being planned. It was found that the Hopkins & Allen Co. of Norwich, Connecticut, was under contract by foreign interests that controlled the Berthier manufacturing rights. It was estimated that the firm could start producing within 8 months, as it was 80 percent tooled up. Contracts were given for the Army's 5,000 guns. An additional 2,000 were ordered by the Navy for the Marine Corps, and given the designation Mark IV. This division of Hopkins & Allen had been incorporated, after receiving the contract, under the name of the United States Machine Gun Co. But financial and other complications arose and the parent firm was forced to drop all plans for manufacturing the weapons. As no other source was available that could give any promise of delivery within a reasonable time, all contracts were canceled. Consequently the guns were never manufactured in the United States, except for a few handmade pilot models.
This weapon is one of the best examples of a good idea developed at a time of peace when its perfection was cut short by lack of interest and money for development. When it was urgently needed in war, it had still not been proved to a point that justified the expensive and time-delaying job of tooling up to make the components with the precision demanded of such a weapon.
Had any country, at the introduction of the Berthier 1908 model, seen fit to function fire and correct the inevitable errors of design that appear during this experimental stage, it undoubtedly would have had in its possession at the beginning of World War I one of the world's most reliable and efficient machine rifles. There is very little question that the mystery of mass production to Europeans, and especially the French, was the contributing factor that made them treat the gun as being simply non-existent. That the basic principles were sound is shown by the fact that at a much later date several battle-tested light machine guns and rifles have used identically the same operating features first presented by Berthier in his two designs of machine rifles."
Overview
The Berthier automatic rifle is a light machine gun that is gas operated and locked by the "prop-up" method. That is, a part of the bolt when in battery is cammed in a vertical plane by the gas piston arm that actuates it as it continues on in a horizontal path. The barrel and receiver are designed so that the gun can use both air and water cooling. It is fed from a 30-cartridge clip located on top of the receiver. The cocking lever is placed on the side of the breech cover, allowing the operator to pull it to the cocked-bolt position, where it is held until released by the trigger. The firing pin, being attached to the gas-piston-actuating arm, detonates the primer from the continued forward travel of the gas-piston arm after it has cammed or "propped" the bolt up into locking position.
The main component parts may be divided for purposes of description into four main assemblies: Barrel group, consisting of the barrel, firing regulator, and gas block; receiver components, being the gas cylinder, buffer, trigger mechanism, and shoulder stock; recoiling parts, consisting of the bolt, piston, and driving spring; and the feed, which is in the form of a semicircular spring-loaded magazine.
All of the barrel assembly is easily detached as a unit. A trap, called the gas block, located about one-third of the way back from the muzzle, houses the cylinder and when removed can be inspected or readily cleaned. The group also has a regulator that has four settings to allow additional gas pressure to be vented to the face of the operating piston.
The receiver is milled from solid stock, the front being threaded to take the barrel, below which is constructed the gas cylinder. A recess is cut in the rear into which can be fitted a detachable stock, while a rectangular piece is formed on (op of the receiver which locks the magazine in place. An ejection slot in the right side of the receiver is closed by a spring-loaded catch except at the time of firing. Immediately behind the magazine housing is the locking shoulder, consisting of a transverse piece of case-hardened steel, set into the roof of the receiver and beveled on its leading lower edge to engage the rear of the tilted bolt. There are also four additional removable hardened cams (these comprise the feed piece) and the bullet guides that govern the cartridge's position on approaching the chamber. A recess to house the buffer is milled at the rear above the mainspring tunnel. This absorbs surplus energy and accelerates the return to battery of the recoiling bolt and gas piston assembly.
The recoiling group is summarized as follows. The head of the piston is slightly cupped with three annular grooves cut into the body to prevent formation of carbon. Its rear is constructed with a projection to form what is known as the cross head. This carries two cams which engage with inclined grooves inside the bolt. A third cam in the rear, known as the actuating cam, fits into a recess in the rear of the bolt body. A flat is cut on the bottom of the cross head with a notch to contact the sear. In front of the cross head is a shoulder to engage the piston stop cut into the receiver. It holds the entire assembly in the rear position when the trigger is released.
The bolt is a long rectangular block that not only slides horizontally between its recesses in the receiver wall but at the end of its travel is allowed a certain degree of tilting in a vertical plane. It is milled out on the rear underside to permit insertion and necessary lateral movement of the cross head. A groove is also cut on the bottom forward part to furnish a slideway for the lock lifting cam. The extractor is located on the right side and the feed guide on the top portion.
The left side of the bolt is cut away sufficiently to accommodate the ejector. The rear upper part of the piece that engages the locking shoulder is cut with a corresponding angle and casehardened to coincide with its mating part in the locking shoulder. The cocking piece on the right side of the gun does not form part of the recoiling group. In order to cock the piece, the handle is drawn to the rear and its catch engages the notch in the guide key on the right side of the cross head. This pulls both bolt and piston back together until the latter engages the sear. The cocking lug is then pushed forward until it snaps into a oneway arrangement that prevents its recoiling with the operating mechanism.
To fire the Berthier gun, a loaded magazine is slipped into a recess on top of the barrel until it engages its holding catch. The charging knob 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 in the cannelure. Coincidental to 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 or 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 the rear of the bolt up and against the locking step in the receiver body.
This swinging, or propping up, of the rear end of the bolt 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 bolt 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 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 rear of the bolt against the locking step. The rear of 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 through the opening and to the right. 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.
Gallery
References
- The Machine Gun, History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons by George M. Chinn Lieutenant Colonel, USMC PART III FULL AUTOMATIC MACHINE GUN DEVELOPMENT
- [1]
- [2]
- [3]
