Patent GB-560813-A (GB)
Title: Improvements in firearms
IPC: F41A1/04
Filed: 1942-05-21
Abstract: 560,813. Automatic guns. MOODIE, G. F. A. PIGOT-. May 21, 1942, Nos. 6897, 14767 and 15007. [Classes 92 (i) and 92 (ii)] An automatic gun is provided with means for feeding charges of an explosive liquid propellant by pressure or suction successively into a combustion chamber in the breech bolt, and means for igniting the charges to propel projectiles previously inserted into the barrel by the breech bolt. The liquid propellant is injected through ducts in the breech bolt or chamber into a forwardlyopen cavity in the bolt by a pump automatically operated by the breech bolt as long as the trigger is pulled, and the cavity is closed by the projectile as this is thrust forward by the bolt. Fig. 2 shows in sectional plan the invention applied to a 20 m.m. automatic cannon, the breech bolt 8, with combustion chamber 4 and projectile 5, being shown with the bolt in the cocked position. During rearward cocking movement of the bolt, a pin 106 moves a slide 105 which acts through links 111 to operate a transverse feed slide 112 the pawls of which feed a projectile from a hopper 6 to the gun breech. A rearward extension of the bolt forms a pump piston 13 which, during forward movement of the bolt, sucks the liquid propellant from a reservoir through valve 100, this liquid on rearward movement of the bolt being forced through a valve 99 into the annular space surrounding the piston rod 17. On release of the trigger, the bolt is moved forward by the return spring 9 and the liquid is forced into a cavity in the breech block through ducts 16 and valve 15. The liquid first passes behind a floating piston 79 in the cavity and then into the chamber 4 through passage 80 in the piston. On closure of the breech, a spark passes across leads 21a and fires the propellant, the pressure acting on the piston 79 to sustain the feed of propellant as the projectile passes down the barrel. The charge may be fired by a firing pin which strikes a cap on the base of the projectile. The gun is arranged for cocking and firing by remote control. Fig. 7 shows a modification with breech closed in which the projectile feed is by a corded belt 96, the cord being severed by a sliding projectiledepressing feed member 69 operated during the opening movement of the bolt through a slide 46 which normally closes the passage between the breech and magazine. The connection 49 between the bolt and the slide 46 is tripped as the breech continues to open and the slide then closes under the action of a spring 71, a lever 91 being meanwhile operated to feed the shells forward in the magazine. In a modification, the charge is fired by current obtained by an armature on the breech bolt moving during the gun action relatively to a magnetic field produced by a permanent magnet. The armature may be rotated by a cam during the opening and closing movement of the bolt and the turning movement of the armature may also serve to unlock the bolt prior to its rearward movement by gas-piston action. Rear projections from the gas-piston rod and breech bolt may serve to operate valves for controlling the passage of air under pressure for feeding the propellant from a reservoir,