Page:EB1922 - Volume 32.djvu/301

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The regulation of the speed of the gun is controlled by an escape- ment mechanism, located in the tube (75), which arrests the recoil mechanism and releases it after the catch has been set free of escapement.

This weapon, like the German light machine-guns described later, and unlike those hitherto dealt with, is derived directly from the heavy machine-gun. It is the outcome, therefore, of an effort to increase the mobility of the machine-gun rather than an attempt to improve the fire power of the shoulder rifle. As a true automatic rifle was available in the form of the Chauchat, and as all facilities for the manufacture of typical machine-gun elements were absorbed by the demand for heavy machine-guns, this type was not manufactured on a service scale during the war. It is however interesting as an instance of the machine-gun approximating to the machine-rifle.

FIG. 12. Hotchkiss Machine-Rifle (French).

Madsen Machine-Rifle (fig. 13) is a recoil-operated, air-cooled rifle weighing about 16 pounds. It may be fired either semi- automatically or automatically. The rate of fire when used as an automatic is about 500 shots per minute. The barrel is about 23 in. long, somewhat larger in diameter than the barrel of the ordinary shoulder rifle, and is provided with annular rings and a perforated barrel casing to facilitate cooling. A bipod and a rest attached to the butt steady the rifle when used by a firer lying down. The cartridges are fed from a detachable quadrant-shaped, 4o-round magazine projecting above the gun. A detachable barrel is provided for the purpose of gaining a more sustained fire, the system being to replace the barrel, when it has been excessively heated, by another barrel, and continue the fire while the first barrel is being cooled. It is claimed that the barrel may be changed in from 12 to 20 seconds.

FIG. 13. Madsen Machine-Rifle (Russian).

The action of the mechanism is as follows :

When the gun is loaded, as shown in the figure, and the trigger (76) is pulled, the hammer (77) under the force of the hammer spring (78) strikes the link (79), which transmits the blow to the firing pin and so to the cap. On firing, the barrel (80) and bolt mechanism (81), locked as a unit, recoils, compressing the recoil spring (82) until the link disconnects the bolt from the barrel lock and allows the bolt to recoil sufficiently to cock the hammer, extract and eject the fired cartridge case. The accelerator (83) assists in driving the bolt to the rear as it engages on the accelerator lug (84) during the recoil and transmits the momentum of the barrel and mechanism to the bolt. The accelerator also drives the barrel home during the forward stroke of the bolt.

A safety device (85) controls the trigger. A change lever (86) enables the gun to be fired semi-automatically or automatically.

The Madsen light machine-rifle was designed some years before the war, and for a time all Russian cavalry divisions had automatic rifle sections armed with it. These were abolished before the out- break of the World War and replaced by ordinary machine-gun sec- tions as the lighter weapon was found to be too delicate for the field. The Madsen was, however, again taken into use by the Russians dur- ing the war, and under the name of the " Musket " it formed the armament of the German " Musket battalions "which were created in 1915. Some of these units with their guns were engaged in the battle of the Somme 1916 but apparently the result, in the trying

conditions of the trench-warfare battle, was not very successful. 1 Tests have been made of the Madsen gun at different times in the British and United States armies.

The Lewis Machine-Gun (fig. 14) is a magazine-fed, gas- operated, and air-cooled machine-gun. The ground type, which is used as a light machine-gun, weighs 265 lb., and is capable of firing at the rate of about 600 shots per minute. The ammuni- tion is fed from a drum-type magazine placed over the receiver, and which holds 47 rounds for ground use, or 97 rounds for air- craft use. It was invented by Col. I. N. Lewis of the U.S. army shortly before the outbreak of the World War, and large numbers were purchased by the British Government to supplement the available Vickers (heavy) machine-guns. When the differentia- tion of light and heavy types began, therefore, the British army found itself already provided with a gun of what was judged to be sufficient mobility, handiness and firepower, and the Lewis gun became and remained the standard type of the light machine- gun for the fighting unit of infantry. In the United States, on the other hand, the military authorities determined to adopt the still lighter Browning, and pending the supply of this, the Chauchat as above mentioned. The Lewis gun, thus classed among the heavy machine-guns, was, however, used in large numbers for aircraft, and a few were employed for training pur- poses as well, some 39,000 of U.S. rifle calibre being ordered and produced. For aircraft, the gun was used by the French also, while in 1918 the Germans, who had a high opinion of it, armed some newly formed motor-cyclist units with captured weapons.

The principal feature is the cooling system, which consists of an aluminum radiator having deep longitudinal fins surrounded by a thin tubular casing which projects several inches beyond the barrel and is reduced in diameter at the front end. These parts with the barrel mouthpiece constitute the cooling system. The mouthpiece deflects the powder gases against the interior wall of the forward portion of the radiator casing in such a man- ner as to draw a current of cool air through the open rear end of the casing and along the thin fins from which it absorbs the heat. The heat conductivity and low specific gravity of aluminum combined with the construction described produce a light-weight cooling mechanism^ The Lewis machine-gun is provided with a bipod mount. The over-all length is approximately 51 inches. The muzzle velocity and chamber pressure are approximately the same with a given ammunition as that of the shoulder rifles in which the ammunition is used.

Action: To operate the Lewis machine-gun, a loaded magazine (10-11) is placed in position on top of the gun, and the charging han- dle (8-4) is pulled to the rear until the sear nose (5-8) engages in the sear notch in the rack (8-1 ). The gun is then ready to be fired. When the trigger is pulled and held, the rack and piston (8-6) move forward under the action of the mainspring (9-9), which in unwinding rotates its gearwheel (9-7) and rack to carry the bolt (4-4) forward. As the operating rod moves forward, the front top edge of the bolt strikes the lower edge of the cartridge which is held in the magazine and feed-way, and drives the cartridge forward into the chamber. The locking lugs on the rear of the bolt move clear of the guide slots in the receiver so that the bolt is free to rotate. The locking of the bolt is then accomplished by the striker post coming in contact with the left side of a cam slot in the bolt, which forces the bolt and its lugs to turn one-eighth of a turn to the right. The extractor springs over the rim of the cartridge case (or the cannelure if rimless) as the bolt forces the cartridge in the chamber. The magazine is held by the rebound pawl (6-8) during the forward move of the bolt and piston. The feed operating arm (7-5) acted upon by the feed operating stud (41) on the rear of the bolt, returns to its normal position during the forward motion of the bolt ready to feed the next cartridge. When the bolt has been completely locked, the striker is free to drive for- ward and fire the cartridge. When the cartridge is fired the mech- anism remains locked until immediately after the bullet has passed the gas port in the barrel (31). Thereupon a portion of the powder gases enters the gas regulator cup (38) and thence through a small aperture 2 reaches the front of the piston (8-6). The force of the ex- panding gases drives the piston to the rear and through the action of the rack, rewinds the mainspring (99). During the backward motion, the striker post, which is also carried on the rack, moves

1 In 1918 the Musketenbataillone were reformed as ordinary heavy machine-gun units.

solid matter carried in the gas and to prevent fouling of the gas chamber. The size of the aperture can be adjusted as required.
 * The function of the gas regulator cup is to act as a well for any