ES356236A1 - Breechcase for firearm - Google Patents

Abstract

An automatic or semi-automatic firearm comprises a substantially cylindrical breech mechanism 1 arranged to reciprocate in a breech case 2 which has, towards its rear end, a portion internally and externally of rectangular cross-section. A spent cartridge ejection opening 7 is provided in one, 3, of the small sides of the portion and the large sides are each provided with a cartridge introduction opening 8 which has two guide surfaces 42 for guiding the breech mechanism 1 and a counter recoil spring 10 in their movements. The four guide surfaces 42 are situated on a common cylinder of revolution whose axis is parallel to the axis of the firearm barrel 16. Two cartridge feed mechanisms (9, Figs. 2, 4, not shown) are mounted one on each side of the firearm one being moved into a cartridge feed position in which cartridges pass through the corresponding cartridge introduction opening 8 to be brought into the chamber 57 of the firearm by the breech mechanism 1 on its return to the firing position. In the construction shown, the breech mechanism 1 comprises a breechblock 11 locked by rotation, a casing 18 formed of two shells and slidable without rotation in the breechcase 2, and a damping device 19. A firing pin 21 within the breechblock 11 is connected to the casing 18 by a spindle 20. The ends of the spindle 20 each carry a roller which co-operates with a skew to effect rotation of the breechblock during its reciprocations (Fig. 4, not shown). The initial cocking mechanism comprises a chain actuated by a crank through a spindle 31. The breechblock 11 carries an extractor 35 and is provided diametrically opposite with a groove 36 for the passage of an ejector 33. The extractor 35 is maintained in position by a leaf-spring 37. The fastening and control of the feed mechanisms are arranged as in Specification 1,191,856 and the cartridge belt advancement mechanism in each feed mechanism may be of the type described in Specification 963,119. The drive of the feed mechanisms comprises a fork 89, one limb of which co-operates with a roller of a lever of the feed mechanism in the cartridge feed position while the other limb is dissociated from the equivalent lever of the other feed mechanism (Figs. 2, 4, not shown). The fork 89 reciprocates with the barrel 16 and sleeve 15 assembly, the movement of the fork being damped in the recoil movement by a piston assembly 99, 100, 105 working in a cylinder in the fork. The pistonrod 101 merely abuts a member 102 of the casing and thus the movement of the fork is not damped by this arrangement on its return stroke. The ejector 33 of the firearm has a cartridge striking surface 109 and a projection 112, the projection firstly urging the spent cartridge to pivot upwardly before the striking surface ejects the cartridge through the ejection opening 7. A spring-loaded sear 26 may be withdrawn and held out of the path of the breech mechanism 1 by cam 67. A damping spring 66 is also provided for the sear.