Patent GB-400588-A (GB)
Title: Improvements in recoil operated small arms
IPC: F41A3/44
Filed: 1932-04-21
Abstract: 400,588. Automatic smallarms. CHEVALLIER, A.L., Llangarron, Ross, Herefordshire. April 21, 1932, No. 11435. [Classes 92 (ii) and 119.] Relates to automatic firearms in which the breech-action is controlled by an inertia member, and consists mainly in a breech mechanism comprising a sliding breech block normally locked by an intermediate member or brace slidably connected with an inertia member, the arrangement being such that when a shot is fired, the inertia member first moves forward relatively to the other parts and is then thrust back by a spring whereupon the inertia member is moved upward by oblique slots and lifts the brace to unlock the breechblock. As shown in Fig. 1, the breech-block 3 is held at its rear end by the brace 20, which has oblique surfaces 21 in contact with corresponding surfaces in the sides of the breech frame, the inclination of these surfaces being about 71 so that the surfaces jam under the recoil pressure but can slip when this pressure has been reduced. In addition, the brace is held in place by the inertia member 27, which is slidably connected with the brace and has pins 29 in engagement with slots 30 in the breech frame. Fingers 28 depend from the front end of the inertia member and engage behind lugs upstanding from a so called conveyor 24 resembling a thimble, which fits into the breech-block and lies between a spring 25 acting on the breech-block and a spring 26 tending to retract the firing-pin 2. When a shot is fired, a lug 44 on the firing-pin bears on a shoulder on the brace adding its support to the jamming action of the oblique surfaces 21 while the brace is still positively locked by the inertia member which moves forward against a spring 31 and at the same time moves the conveyer forward against the spring 25. After this, the inertia member is moved back by the spring 31, and the inclined parts of the slots 30 then lift the member up and with it the brace; and the conveyer and the breech-block are thus unlocked. The rearward movement of the inertia member is stopped by shoulders 92 thereon abutting against shoulders 93 on the sides of the breech frame. The rearward opening movement of the breech-block against a spring 35 cocks a hammer 4 by means of a projection 97 on the firing-pin and extracts the spent cartridge by means of an extractor 38; and a spring urged ejector 39 ejects the cartridge upwards. A fresh cartridge is fed from a magazine 42 ; the breech-block moves forward again ; and the brace 21 under the influence of a spring 91 is moved down again to the locking position. For safety, the firing-pin 2 which is confined in the breechblock by a pin and slot 46 is retained in a retracted position by a bell-crank lever 47, which is deflected by the hammer 4 just before it strikes the firing-pin. The pivoted hammer 4 is connected to a rod 6 influenced by a spring 5, and is held cocked by a sear 7 to which is pivoted a member 17, 19 influenced by a spring 11 through a rod 10 and co-operating with the nose 14 of a trigger 15. The hammer can be locked or unlocked by a spindle 51 with a flat side, which can be turned by a handle 52, Fig. 4, the boss of which is cam shaped and operates a spring plunger 53 to lock the inertia member 27 when the hammer is locked. The hammer is also locked by the engagement of a tooth 60 on the rod 6 by a pawl 59 on a bell-crank 58, 57, so long as the inertia member is in a retracted position and deflects the crank 57 ; this prevents friction between the hammer and the breech-block. Similarly to prevent serious friction between the fingers 28 and the returning breech-block, the inertia member is held back by a catch 71 on a lever 68 until the breechblock is closed and deflects the other end 69 of the lever 68. The catch 71 is put in action when the breech-block begins to recoil and the end of the lever 68 on which the catch is situated. The lever 68 may also be spring operated and may be fitted with an ejector. Still further safety is provided by a transversely sliding trigger lock 65, which can be placed in three different positions. In one position, it locks the trigger; in a second position for continuous firing, it allows a partial pull of the trigger which keeps the hammer released so long as the trigger is pulled ; and in a third position for single shot firing, it allows a full pull of the trigger which makes the nose 14 slip past the sear 17 after the hammer has been released. The automatic action of the inertia member may be prevented by means of a vertically sliding locking bolt 79. The breech-mechanism may then be operated by a handle 82, Fig. 5, attached to two slides 81, 84, the slide 81 having a lug 83 for lifting the inertia member 27, and the slide 84 having a heel 85 for retracting the breechblock. The inertia member is then held back by a notch 95 therein falling over the lug 83, and the breech-block is held in the retracted position by the cartridge follower 89 of the magazine until this is depressed by the insertion of a fresh cartridge. The follower 89 also holds the breech open when the magazine is emptied by automatic firing. An extension 87 of the slide 81 serves as a dust cover for the slot 88 in the breech frame required for the co-operation of the slides 81 and 84. The rear end of the breech-action is closed by an abutment 37 hinged at 73 and locked in place by a spring operated catch 76, which can be disengaged by the insertion of a pin in a hole 78. The abutment 37 supports a plate 36 which takes the thrust of the recoil spring 35. For opening and inspecting the breech-action, the inertia member 27 which forms a cover is first raised and held raised by the bolt 79, which for this purpose is moved to a second higher position, the rear abutment 37 is swung open, the stock and trigger plate are turned about a hinge 96 relatively to the barrel and magazine, and the breech-block, the conveyor, the firing-pin, the rear plate 36 and the springs of these parts are withdrawn through the open rear end. In a shot gun provided with a similar breech-action, the magazine is a tube 101, Fig. 17, under the barrel. The cartridges are delivered one at a time past gates 115 to a spoon 106, which lifts the cartridge into line with the breech-block and is retained lifted by a pivoted catch until this is deflected by the return of the inertia weight to the normal locking position. A flap 111 pivoted to the spoon at 109 and provided with a heel 110 serves to stop the breech-block in the open position when the magazine is empty ; and a finger 112 on the conveyer holds the heel 110 down when the breech-block moves forward. For those who are accustomed to a loading handle slidably mounted on the magazine, such a handle is provided in addition to the handle 82 and is fitted with a slide which when the handle is pulled back bears on and operates the slide 84. A spring catch serves to hold the sliding handle in the forward or the backward position. In a modification, Fig. 27, allowing for single shot firing only, there is no pivoted hammer, and the firing-pin 2 is itself held cocked by a sear 127 adapted to be pulled and released by a slip catch 131, which is pivoted at 134 to the trigger 15 and is deflected forward by a fixed abutment 133 when drawn down by a pull on the trigger. The catch 131 is locked by a crank 136 until the inertia member 27 has returned to the breech locking position.