Patent GB-1428027-A (GB)
Title: Air guns
IPC: F41B11/646
Filed: 1973-04-06
Abstract: 1428027 Air guns BSA GUNS Ltd 5 July 1974 [6 April 1973] 16674/73 Heading F3C An air gun has a reciprocable cylinder 4, Fig. 1, a piston 5 reciprocable within the cylinder, an actuating spring 10 disposed between the cylinder and the piston so as to move the cylinder and the piston in opposite directions from a cocked position in which the spring 10 is compressed therebetween and to thereby compress air within the cylinder, and a trigger mechanism operable to release the cylinder and the piston from said cocked position, the cylinder having a passage 20 therein which moves into alignment with a transfer passage 21 leading to a barrel 3 of the gun to release pressurized-air from the cylinder to the barrel 3 when the cylinder has moved a predetermined distance after its release from the cocked position by the trigger mechanism. The cylinder 4 and the piston 5 are held in the cocked condition by a roller 12 which locates in a slot 13 in the wall of the cylinder 4 and engages a detent 14 in the piston 5, the roller being held in engagement with the detent by a sear 15 which is pivotally mounted at 16, has one end abutting the roller 12 and has the other end abutting a trigger catch 17. The latter is pivotally mounted at 18 and is actuatable by a trigger 19, the trigger catch 17 and the trigger 19 forming the trigger mechanism. After the cylinder and piston have completed their relative movements from the cocked position, under the action of the spring 10, the cylinder is returned to the cocked position by a spring 23 and the piston is returned to the cocked position by a slider 26, Fig. 3, having a projection 25 engageable with an axial slot 24 in the piston and which is actuated by a manually-operable lever 28, via a link 27, the cylinder 4 being retained by a catch mechanism prior to the return of the piston 5. The catch comprises a spring-loaded plunger 30 which is engageable with an aperture 31 in the gun and is releasable by a plunger 34 slidably mounted in the slider 26. The sear 15, Fig. 1, and the trigger 19 are urged by a spring 33, via the trigger catch 17, so as to maintain said one end of the sear in engagement with the roller 12 as it moves back into engagement with the detent 13 in the piston and to move the trigger mechanism back into engagement with the sear when the piston and the cylinder have returned to their cocked positions. The breech 22 is closable by a pin 35 which is slidable to the position shown in Fig. 5 to allow the insertion of a pellet into the breech, and is abutable by the sear 15 when the firing mechanism is un-cocked as shown in Fig. 3 to prevent re-loading in this condition. The sear 15 abuts the underside of the pin 35 when the firing mechanism is cocked and the breech is opened, as shown in Fig. 5, to prevent the firing of the gun in this condition. In use the pulling of the trigger 19, Fig. 1, causes the trigger catch 17 to move anti-clockwise and disengage from the sear 15. The roller 12 moves radially outwards, slightly rotating the sear 15 in a clockwise direction, under the action of the spring 10 and, when the roller 12 is disengaged from the detent 14, the spring 10 extends to move the cylinder 4 rearwardly and the piston 5 forwardly, air being compressed in chamber 37 of the cylinder. The movement of the cylinder and the piston terminate when the piston head contacts the end of the cylinder 4, Fig. 2, at which instant the cylinder 4 is at its rearwardmost position in which it abuts a rubber buffer 39. The passage 20, in the cylinder connects with the transfer passage 21 and pressurized-air passes from the chamber 37 to the breech 22 and propels a pellet along the barrel 3. The cylinder 4 is then moved forwardly by the spring 23 to the position shown in Fig. 3 where the firing mechanism is in a stable uncocked position. Recocking is effected by the lever 28.