Part 7 (1/2)
The latest type, fitted with an electro-motor, will fire at the _rate_ of one thousand rounds per minute, and eighty rounds have actually been fired within ten seconds! It is not, however, safe to work these machine-guns so fast, as the cartridges are apt to be occasionally pulled through unfired and then explode among the men's legs. The automatic guns, on the contrary, as they only work by the explosion, are free from any risk of such accidents.
The feed-drums contain 104 cartridges, and can be replaced almost instantly. One drumful can be discharged in 5-1/4 seconds. The small-sized Gatling has a drum-feed of 400 cartridges in sixteen sections of twenty-five each pa.s.sed up without interruption.
The gun is mounted for use so that it can be pointed at any angle, and through a wide lateral range, without moving the carriage.
_The Gardner._--The Gatling, as originally made, was for a time superseded by the _Gardner_, which differed from it in having the barrels (four or fewer in number) fixed in the same horizontal plane.
This was worked by a rotatory handle on the side of the gun. The cartridges slid down a feed-case in a column to the barrel, where they were fired by a spring acting on a hammer.
_The Nordenfelt._--Mr. Nordenfelt's machine-gun follows this precedent; its barrels--10, 5, 4, 2, or 1 in number--also being arranged horizontally in a strong, rigid frame. Each barrel has its own breech-plug, striker, spring, and extractor, and each fires independently of the rest, so that all are not out of action together.
The gun has a swivelled mount easily elevated and trained, and the steel frames take up the force of the discharge. In rapid firing one gunner can work the firing-handle while another lays and alters the direction. The firing is operated by a lever working backwards and forwards by hand, and the gun can be discharged at the rate of 600 rounds per minute.
_The Hotchkiss._--The Hotchkiss gun, or revolving cannon, is on a fresh system, that of intermittent rotation of the barrels without any rotation of breech or mechanism. There is only one loading piston, one spring striker, and one extractor for all the barrels. The shock of discharge is received against a ma.s.sive fixed breech, which distributes it to the whole body.
Like the _Nordenfelt_, however, it can be dismounted and put together again without the need of tools. The above pattern throws 1 lb.
projectiles.
_The Maxim._--Differing from all these comes the _Maxim_ gun, so much in evidence now with both land and sea service. It is made up of two portions:--
(1) _Fixed_: a barrel-casing, which is also a water-jacket, and breech-casing.
(2) _Recoiling_: a barrel and two side plates which carry lock and crank.
This recoiling portion works inside the fixed.
The gun is supplied with ammunition by a belt holding 250 cartridges pa.s.sing through a feed-block on the top. Its mechanism is worked _automatically_; first by the explosion of the charge, which causes the barrel to recoil backwards and extends a strong spring which, on rea.s.serting itself, carries it forwards again. The recoiling part moves back about an inch, and this recoil is utilised by bringing into play mechanism which extracts the empty cartridge-case, and on the spring carrying the barrel forward again moves a fresh one into position. Under the barrel casing is the ejector tube through which the empty cartridge-cases are ejected from the gun.
The rate of fire of the Maxim gun is 600 rounds per minute. Deliberate fire means about 70 rounds per minute; rapid fire will explode 450 rounds in the same time. As the barrel becomes very hot in use the barrel-casing contains seven pints of water to keep it cool. About 2000 rounds can be fired at short intervals; but in continuous firing the water boils after some 600 rounds, and needs replenis.h.i.+ng after about 1000. A valved tube allows steam, but not water to escape.
The operator works this gun by pressing a firing-lever or b.u.t.ton.
After starting the machine he merely sits behind the s.h.i.+eld, which protects him from the enemy, directing it, as it keeps on firing automatically so long as the bands of cartridges are supplied and a finger held on the trigger or b.u.t.ton. By setting free a couple of levers with his left hand, and pressing his shoulder against the padded shoulder-piece, he is able to elevate or depress, or train the barrel horizontally, without in any way interfering with the hail of missiles.
We use two sizes, one with .45 bore for the Navy, which takes an all-lead bullet weighing 480 grains, and the other with .303 bore, the ordinary nickel-coated rifle bullet for the Army. But as the Maxim gun can be adapted to every rifle-calibre ammunition it is patronised by all governments.
The gun itself weighs 56 lbs., and is mounted for use in various ways: on a tripod, a field stand, or a field carriage with wheels. This carriage has sixteen boxes of ammunition, each containing a belt of 250 cartridges, making 4000 rounds altogether. Its total weight is about half a ton, so that it can be drawn by one horse, and it is built for the roughest cross-country work. A little machine, which can be fixed to the wheel, recharges the belts with cartridges by the working of a handle.
For s.h.i.+ps the Maxim is usually mounted on the ordinary naval cone mount, or it can be clamped to the bulwark of the deck or the military ”top” on the mast.
But there is a most ingenious form of parapet mounting, known as the garrison mount, which turns the Maxim into a ”disappearing gun,” and can be used equally well for fortress walls or improvised entrenchments. The gun is placed over two little wheels on which it can be run along by means of a handle pushed behind in something the fas.h.i.+on of a lawn-mower. Arrived at its destination, the handle, which is really a rack, is turned downwards, and on twisting one of the wheels the gun climbs it by means of a pinion-cog till it points over the wall, to which hooks at the end of two projecting bars firmly fix it, the broadened end of the handle being held by its weight to the ground. It is locked while in use, but a few turns of the wheel cause it to sink out of sight in as many seconds.
The rifle-calibre guns may also be used as very light horse artillery to accompany cavalry by being mounted on a ”galloping carriage” drawn by a couple of horses, and with two seats for the operators. The carriage conveys 3000 rounds, and the steel-plated seats turn up and form s.h.i.+elds during action.
It is interesting to notice that an extra light form of the gun is made which may be carried strapped on an infantryman's back and fired from a tripod. Two of these mounted on a double tricycle can be propelled at a good pace along a fairly level road, and the riders dismounting have, in a few moments, a valuable little battery at their disposal.
The _Pom-pom_, of which we have heard so much in the late war, is a large edition of the Maxim automatic system with some differences in the system. Its calibre is 1-1/2 inches. Instead of bullets it emits explosive sh.e.l.ls 1 lb. in weight, fitted with percussion fuses which burst them into about twelve or fourteen pieces. The effective range is up to 2000 yards, and it will carry to 4000 yards. An improved _Pom-pom_ recently brought out hurls a 1-1/4 lb. sh.e.l.l with effect at a mark 3000 yards away, and as far as 6000 yards before its energy is entirely exhausted. The muzzle velocity of this weapon is 2350 feet a second as against the 1800 feet of the older pattern. They both fire 300 rounds a minute.
The _Colt_ automatic gun is an American invention whose automatic action is due to explosion of the charge, not to recoil. The force by which the motions of firing, extracting, and loading are performed is derived from the powder-gases, a portion of which--pa.s.sing through a small vent in the muzzle--acts by means of a lever on the mechanism of the gun.
This is also in two parts: (_a_) _barrel_, attached to (_b_) breech-casing, in which gear for charging, firing, and ejecting is contained. The barrel, made of a strong alloy of nickel, has its cartridges fed in by means of belts coiled in boxes attached to the breech-casing, the boxes moving with the latter so that the movements of the gun do not affect it. These boxes contain 250 cartridges each and are easily replaced.