Patent GB-1423153-A (GB)
Title: Firearms
IPC: F41A17/78
Filed: 1972-12-01
Abstract: 1423153 Safety device for a firearm BSA GUNS Ltd 27 Nov 1973 [1 Dec 1972] 55673/72 Heading F3C  A firearm which is fired by the pivotal movement of a hammer, under the action of a spring, when the hammer is released from a cocked position by a trigger, comprises a safety means which is movable to and from a safe position in which it forms an abutment preventing pivotal movement of the hammer under the action of the spring, the safety means and the hammer having interengaging surfaces whereby the hammer, in being moved to its cocked position, engages and moves the safety means to the safe position, and means independent of the trigger for moving the safety means from the safe position. The safety means is a member which has a slot therein and is rotatable between a firing position where the slot allows part of the hammer to pass therethrough when it is released from its cocked position and a safe position in which the slot no longer offers passage to the part of the hammer. In an embodiment an air pistol has a piston 1, Fig. 1, actuated by a spring 2 to compress air within a cylinder 3. The latter has a passage 4 formed therein which aligns with a breech 5 of a barrel 6 so that compressed air can pass from the cylinder 3 and drive a projectile (not shown) through the barrel 6. The piston 1 is held in a cocked position, the spring 2 being compressed, between the piston 1 and a wall 7 of the cylinder 3, by a trigger mechanism comprising a trigger 8 pivotally mounted on a pin 9, a hammer 10 which, along with an intermediate sear 11, is pivotally mounted on a pin 12, and a main sear 13 which is pivotally mounted on a pin 14. The trigger mechanism is housed between side-plates 15 and 16, Fig. 2, which are secured to the cylinder 3 by screws 17. The stepped portion 18, Fig. 1, of the main sear 13 engages a sear edge 19 of a slot 20 in the piston 1 and is prevented from pivoting by an arm 21 of the intermediate sear 11 which engages the lower face 22 of the free end of the main sear 13. The hammer is retained cocked, against the action of a two-legged torsion spring 23 which engages the hammer 10 and the intermediate sear 11, by a trigger bar 24, Fig. 5, which engages a detent 25 in the hammer. To fire the pistol the trigger is depressed thus disengaging the trigger bar 24 from the detent 25 and allowing the hammer 10 to be pivoted by the spring 23. A projection 26 on the hammer 10 strikes the arm 21 of the intermediate sear 11 to knock it out of engagement with the main sear 13. The latter is disengaged from the piston 1, Fig. 1, by the spring 2 and the piston 1 completes its firing stroke. The trigger load can be varied by a screw 27 in a bore 28 in the trigger 8, which adjusts the force exerted by a spring 29. The safety means comprises a safety-rod 30 which is rotatably mounted in the side-plates 15, 16, Fig. 2, and is provided with a radial groove 31, Fig. 1, which, with the rod 30 as shown permits a portion of the hammer 10 to pass therethrough when the hammer is released by the trigger 8. Fig. 6 shows the trigger mechanism after the pistol has been fired. Cocking of the pistol is by longitudinal movement of the cocking bars 32 which are separated by a spacer 33, Figs. 1 and 2, and are actuated when the barrel assembly is pivoted at 34 about the body of the pistol, this also exposing the breech 5 for re-loading of a projectile. The actuating of the cocking bars 32 is via links 35 which are pivotally connected to the latter and to the barrel assembly. The piston 1 is moved towards its cocked position by the cocking bars 32, each having a stepped portion 36, Fig. 6, engaging an edge 19 of the slot 20 in the piston 1. During cocking of the pistol one of the bars 32 contacts arm 37, Fig. 7, of the hammer 10 to move it in a clockwise direction. An arm 38 of the hammer 10 engages a lip 39 of groove 31 in the rod 30. The arm 21 of the intermediate sear 11 contacts edge 40 of the main sear 13 and is thereby prevented from moving pivotally with the hammer 10, thus tensioning the torsion spring 23. At the end of the cocking operation, the cocking bars 32, Fig. 8, have moved the piston to its rearmost cocked position and the main sear 13 has been moved by the spring 41 so that its stepped portion 18 engages the edge 19 of the groove 20. The intermediate sear has been moved by the spring 23 until its arm 42 abuts the rod 30, the arm 21 of the intermediate sear 11 lying below the free end of the main sear 13. The hammer 10 has rotated clockwise beyond the position shown in Fig. 7, the arm 38 having rotated the rod 30 in a clockwise direction so that the groove 31 is in the position shown in Fig. 8. The barrel 6 is returned to the position shown in Fig. 1, the cocking bars are retracted and the trigger mechanism is in the cocked safe condition shown in Fig. 9, the rod 30 having been moved by the hammer 10 so that the radial groove 31 is out of alignment with the portion of the hammer intended to pass therethrough and the upper lip 43 of the groove 31 engages detent 44 in the hammer 10, the latter being prevented from moving in an anti-clockwise direction. In this condition the trigger 8 may be depressed without firing the pistol. Clearance is provided between the trigger bar 24 and the detent 25 in the hammer 10 to facilitate the re-engagement of the trigger bar 24 and the detent 25. The pistol is changed from the cocked safe condition as shown in Fig. 9 to the cocked firing condition shown in Fig. 1 by rotating the safety rod 30 in an anti-clockwise direction by an external operating lever (not shown) secured thereto.