Cartridges are automatically fed into the gun by means of a belt containing 250, running from a box attached to the left side of the breech casing.
The automatic action of the gun is effected by means of the pressure of the powder gases in the barrel. There is a small radial vent in the barrel near the muzzle, opening downward from the bore. This vent is closed by a piston which fits in the gas cylinder surrounding the outer edge of the vent. The piston is pivoted to the gas lever so that it adjusts itself to the gas cylinder while the lever swings in a vertical plane.
The belt is inserted from the left; the lever thrown downward and rearward as far as it will go. This opens the breech and feeds the first cartridge from the belt to the carrier; the lever is then released, and the spring causes it to swing forward, close the vent and transfer the cartridge from the carrier to the barrel; also cocking the hammer, closing and locking the breech.
Plate VIII.
Gun mounted on Tripod, showing Belt passing out.
(Right Side.)
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.