On pulling the trigger the cartridge is fired. After the bullet has passed the vent and before its exit from the muzzle, the powder gases expand through the vent upon the piston and gas lever, which in turn act on the breech mechanism, opening the breech, ejecting the shell and feeding to the carrier another cartridge. The gas lever, returning, under the action of the retractor spring, forces the cartridge into the chamber, closing and locking the breech. If, instead of releasing the trigger, it is held back, the same operation will be repeated as long as cartridges are supplied, producing continuous fire at the rate of 400 shots or more per minute. A safety lock secures the hammer, the latter being also used as a piston for an air-pump, forcing a strong jet of air into the chamber and through the barrel, removing all residue after the empty shell is ejected. =The mainspring, firing-pin and extractor= can be easily replaced. =The mount= consists of two principal parts:— (_a_) Saddle with toothed arc. (_b_) Yoke. =The saddle=, in which the gun rests, is pivoted to the yoke by means of the axis bolt, so as to swing in a vertical plane. The gun is held in position on the saddle by the gun pin, which is inserted with its handle vertical; in any other position of the handle the gun is held secure by the gun pin lock screw. =Changes of elevation= are made by means of the worm gear, which engages in the teeth of the arc, and is operated by the hand wheel, being secured at any angle by the arc clamp. The lower part of the yoke is in the form of a spindle, and fits in the socket of the tripod, being secured by a spindle washer and spindle washer bolt. =The tripod= consists of a socket to which the legs are hinged. The two front ones being interchangeable, brass shoes are attached to prevent their sinking into the ground during firing. A seat is attached to the lower portion of the rear leg, also a leather tool bag containing spare parts, etc. Equipment. 4 feed belts (capacity 250 rounds per belt). 4 feed boxes, for feed belts. 1 leather tool bag, containing the spare parts and accessories. Spare Parts. 1 main spring. 1 hammer. 1 cartridge extractor and spring. 1 sear spring. 2 firing pins. 2 firing pin springs. 2 firing pin lock pins. 2 shell extractors. 2 shell extractor springs. 2 shell extractor pins. 2 handle locks. 2 bolt pins. 2 trigger springs. 4 cotter pins for piston-pin. 1 piston spring. Accessories. 1 oil can. 1 combination spanner and screwdriver. 1 jointed cleaning rod. 1 combination operating handle and screwdriver 3 drifts. Instructions for Operation. Attach box in firing position on the left side of mount.