The piston F, enlarged and suitably shaped at the rear, actuates the breech-block H and firing pin or striker J; and, by suitable cam grooves (f) at about the centre of its length, works the larger feed-wheel U of the feed-box S; the smaller wheel U on the same axis in turn imparting a step-by-step motion to the metal feed-strips, each containing 30 cartridges, so that fresh cartridges are placed one by one before the face of the breech block ready to be pushed into the breech when the fired cartridge has been extracted and ejected.
On the under surface of the piston F, in rear, is a recess or sear (f) in which the nose of the trigger N engages, holding back the piston when it has been driven back by the gases. As already stated, a lug on the under surface just in rear of the cam (f) engages with the front of the mainspring.
| Fig. 12.—Maxim Gun Mechanism. |
| Fig. 13.—Maxim Feed-block. |
Taking first the position shown in fig. 15 with the breech closed and locked and the cartridge fired, it will be seen that the breech is locked by the upper cam (f′), on the end of the piston, F, having caused the movable locking-dog (h) to fall and bear against the recoil blocks Z (see fig. 14 also) on the walls of the receiver or frame B. Consequently the breech is not unlocked until the piston has moved sufficiently to the rear for the lower cam (f′) to lift the locking-dog (h) clear of the recoil blocks Z. As the piston F is not actuated by the gases until the bullet has passed the port (c), and then has to move a short distance before the locking-dog is raised, the bullet is clear of the muzzle before the breech is unlocked.
As the piston continues to recoil it draws back the striker J and then the breech-block H, and is then caught and retained by the engagement of the sear (f) with the trigger N, and the position assumed is that shown in fig. 14.
| Figs. 14, 15, 16.—Hotchkiss Gun Mechanism. |
From the head or nose-piece I of the breech-block projects the claw K of a spring extractor which, as the cartridge is pushed home by the breech-block, seizes it, extracting the fired case when the breech-block is withdrawn. Ejection of the fired case is effected by means of the ejector L (fig. 16) which catches against the base of the case, on the opposite side to the extractor claw, and so throws it sideways through the oblong-pointed opening in the receiver just in rear of the breech (see fig. 14).
The platform on the top of the feed-box through which the teeth of the smaller feed-wheel U project, and on which the feed-strips rest, lies below the axial line of the breech-block H, so that the face or nose-piece I of the latter only engages a portion of the base of the cartridge in the feed-strip as it pushes the cartridge into the breech, the bullet of the cartridge being guided into the breech by the incline at the opening of the latter. This point should be specially noted, the object of the arrangement being to enable the under surface of the breech-block to clear the clips which hold the cartridges in the feed-strips. The cartridge therefore, being extracted in the line of the axis of the block, is ejected through an opening above its plane of entry in the feed-strip.
Returning to the position shown in fig. 16, if the trigger be pulled, the compressed spring M reacts and drives the piston forwards, carrying the breech-block with it, the latter in turn driving a cartridge in front of it out of the feed-strip. When the block and cartridge are home, and not till then, the piston completes its travel, the upper cam (f′) locking the dog (h), and the firing-pin protrudes and fires the cartridge. Anything, therefore, which prevents the breech-block from being home against the breech, or the locking-dog from falling in front of the recoil blocks Z, renders firing of the cartridge impossible. Clearly if the trigger be kept depressed the action becomes automatic.