about one inch to the rear in a straight s]ot in the bolt, which, there- fore, it does not affect while the bullet is traversing the final space between the gas port and the muzzle; but after the striker post has passed through the straightway of the bolt, it comes in contact with the right side in the cam slot in the bolt and unlocks the bolt and drives it to the rear. In unlocking the bolt is rotated and the locking lugs come into line with the guide slots in the receiver. Lastly the extractor (4-3) withdraws the empty cartridge case which is thrown out by the ejector (2-3), a flat lever pivoted in the centre and actuated by the feed operating stud (4-1) striking its rear end. This stud,
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6-6 Stop 6 Rebound Potr/Spr. 6 5 feed Cover 2-3 Qector S-S EjeccorCot 7-5 Feed Operating Arm
heavy machine-gun (M.G. 08), which is of the Maxim type, without any change in the essentials of the system (for which see MACHINE-GUN, 17.237). A serviceable light machine-gun was made in large quantities and with the least possible delay, and the German authorities determined to lighten the existing material, for which manufacturing facilities were already avail- able, rather than embark on the experiments and tool and gauge making that would have been necessary if a new type had been
BacMgM 6 2 * Cartndge Guide
rrel Mouthpiece 4 Radiator Casing Showing Siphoninq action of escaping gases
3-aa,s,ulati>,Cvt 3-S 001 Ktftilotor Xy
8-4 Charging Handlt -1 Fetd Operating Stud
FlG. 14. Lewis Machine-Gun.
which is carried by the bolt, also acts on the underside of the feed operating arm (75) and moves the arm to the left. By means of this arm and the feed pawl (7-2) that it carries, a cartridge from the magazine is brought under the cartridge guide (6-24) and into the feeding position in the feed-way in the top of the receiver and is partially turned so as to bring the next cartridge into position, being held in its new position by the stop pawl (6-7), and by the rebound pawl (6-8). The rearward motion of the mechanism is arrested when the bolt comes against the butt tang of the stock, and the bolt, rack, etc., then again move forward under the action of the main- spring, and the cycle of operation is repeated for each shot until the magazine is empty or the trigger is released. When the last cartridge is fired from the magazine, the bolt goes forward and locks with no cartridge in the barrel.
The magazine is a round corrugated pan about 8 in. in diameter carrying 25 upright separator pins. This pan is mounted with an aluminum centre having annular grooves with a spiral step connect- ing each groove, into which the front end of the cartridge fits. The cartridge, being held from rotating by the separator pins, is fed along these grooves up the steps into the gun when the pan is revolved around the magazine centre. The pan is loaded by means of a special loading tool. The feeding of the cartridges being positive instead of depending on springs or gravity, the gun can be used when turned at any angle or upsidg down.
The Lewis machine-gun operates automatically, single shots being fired by quickly releasing the trigger after each shot.
In aircraft the Lewis gun is used as a " flexible gun," i.e., a gun mounted (usually in the observer's pit) so as to fire in any direction in elevation or azimuth. The main differences between the ground type and the aircraft type gun are that the latter has no radiator or radiator casing, has a spade or stirrup-shaped hand-grip in lieu of the shoulder stock, and uses a 97-round magazine. A more efficient type of recoil check is also provided. This consists of a muzzle attachment which is arranged to deflect the powder gases so that they pass out practically at right angles to the axis of the bore. In this way a pressure against the muzzle piece tends to counteract recoil.
No cooling device is provided with the aircraft gun, inasmuch as the fire is in short bursts only and the speed of the aeroplane and the temperature at high elevations provide ample cooling. The aircraft gun fires at a rate of about 750 shots per minute, this higher speed being gained by increasing the gas pressure acting on the piston and the strength of the mainspring which returns the mechanism.
German Light Machine-Gnns 08/15 an d 08/18. The German light machine-gun 08/15 is simply a modification of the standard
sought for. In consequence, the differences between the 08 and the 08/15 are very few. The diameter and contents of the water- jacket are considerably smaller in the light gun than in the 08. Instead of the tripod or sleigh mount, there is a shoulder stock and bipod, and a trigger release and handgrips replace the twin handles and firing gear. Ammunition is belt-fed as in the heavy gun, but the belt (100 rounds) is wound on a reel inside a drum attached to the right of the gun. The weight of the gun with water-jacket filled and bipod, is 40^ lb., or in action with drum and filled belt 515. The Dreyse water-cooled light machine-gun was also used. Its weight was slightly less than that of the 08/15.
Guns of this weight, however, though they might be sufficiently mobile for trench warfare battles, were evidently too heavy for the more open warfare of 1917 and especially 1018, and a new and lighter model called the 08/18 was brought out. In this instead of the water-jacket there is a barrel casing with numerous holes to facilitate air circulation round the barrel. This abolition of positive cooling by water reduced the possibility of sustained fire almost to that of an automatic rifle, but independence of water supply greatly reduced freedom of manoeuvre and the actual reduction in the weight of the gun was considerable (32 lb. as against 40^ in the 08/15).
This gun had been introduced only for cavalry and cyclists when the Armistice was signed. Had the war continued, it would no doubt have replaced the water-cooled weapons entirely.
The Bergmann Light Machine-Gun (fig. 15) in the German army, variously called L.M.G. and L.M.G. 15 n A, is a recoil- operated air-cooled, belt-fed machine-gun, weighing 30 lb. with bipod mount and sling, and fires about 600 shots a minute.
A barrel casing (91) is provided which carries the barrel and also serves as a housing in which the barrel recoils. The cooling of the barrel is assisted by rings which are formed on the barrel to increase the radiating surface. A handle (92) is provided to facilitate carrying the weapon short distances. The belt is fed through the feed-box opening (93) as in the Maxim and other heavy machine-guns.
The principal features of the Bergmann machine-gun are a small cylindrical service-rifle type of bolt and extractor, which may be
