Patent GB-291778-A (GB)
Title: Improvements in or relating to automatic or self-loading guns
IPC: F41A3/82
Filed: 1928-03-20
Abstract: 291,778. Pedersen, J. D. June 9, 1927, [Convention date]. Breech actions, sliding breech-block; protecting from heat of f barrel; stocks. - Relates to automatic guns having a toggle-link recoiloperated breech mechanism, and consists mainly (1) in arranging the toggle so that an initial slight eccentricity thereof when the breech is closed is maintained substantially constant during the initial part of the recoil of the breechblock, which has no positive lock, and (2) in providing the toggle with rolling abutting surfaces through which the firing pressure is transmitted. The bullet leaves the barrel and the opening impulse is imparted to the breech mechanism before the aforesaid initial part of the recoil of the breech-block is completed. After the completion of this initial part of the recoil, the eccentricity increases rapidly and the breech is opened. The breech-block 23, Fig. 4, slides on the receiver 2 and bears against a toggle link 24, which itself bears against a crank 25 abutting against a pivot pin 26 on the receiver. In the closed position, the breech-block 23 and the toggle link 24 have rolling surfaces 31, 30 in contact at x, the toggle link 24 and the crank 25 have rolling surfaces 37, 38 in contact at y, and the crank 25 makes rolling contact with the pivot pin 26 at z. The point y is slightly above the line z - - x. At the beginning of the recoil of the breech-block, the points of contact x, z roll upwards, while the point of contact y rolls downwards, with the result that the eccentricity of the point y relatively to the line z - - x is not substantially changed. After a small initial recoil, a knuckle 32 on the toggle link fits into a socket 33 in the breech-block and forms a pivot between these two members. Later on, the toggle link 24 pivots relatively to the crank 25 on a gudgeon pin 43 of a small link 39, which is connected to the toggle link 24 by another gudgeon pin 40; and the crank 25 pivots round the pin 26. During this recoil movement, a recoil spring 61, Fig. 9, is compressed by a member 52 slidably mounted on the crank 25 and provided with a roller 55, which during the main part of the recoil compresses the spring by riding down a fixed cam face 56. At the end of the recoil, the breech-block abuts against the crank 25 and moves it bodily backwards a short distance, during which the roller 55 is made to ride up the cam 56, thereby making the recoil spring 61 act as a strong buffer for the end of the recoil stroke. The parts are returned to the closed position by the spring 61, and at the end of the closing movement, the roller 55 passes to a steeper part 57 of the cam, which increases the mechanical advantage, of the closing force. A shoulder 58 at the front end of the slide 52 comes over a shoulder 59 on the toggle link when the breech closes and prevents the front end of the crank from swinging too low. The breech mechanism may be worked by hand by means of a handle 60 on the slide 52. The breech-block 23 carries an extractor 72, Fig. 9, an ejector 73, Fig. 3a, a sliding spring striker 68, and a pivoted sear 71. The striker has a firing pin 75 and is under the influence of a coiled spring 69, which takes its abutment against a base-piece 78 bearing against the sear, so that the spring serves the double function of a firing and sear spring. The base-piece 78 projects beyond the rear face of the breech-block and is pushed in when the breech-block comes against the crank at the end of the opening movement; this relieves the interengaging shoulders between the sear and the base-piece of shock at the end of the recoil. The toggle link 24 carries a sear trip 81 controlled by a spring plug 105, a cocking hook 84, and a safety member 85. The cocking hook 84 engages a bent 77 on the striker 68 and is cushioned by a spring plunger against the safety member 85. A horn 101 projects from the cocking hook and pivots in the socket 33 of the breech-block, so that as soon as the recoil begins a backward movement of the cocking hook against its cushion spring accompanies its rotation with the toggle link; and by this combined movement, the hook 84 cocks the spring striker 68, a bent 76 thereon becoming engaged by the sear 71. When the breech is subsequently closed, the firing mechanism may be locked by a lateral displacement of the safety sliding member 85 to the " safe " position. This movement draws the cocking hook 84 backwards against the bent 77 and at the same time brings a shoulder 83 on the hook over a shoulder 82 on the sear; thus both the sear and the striker are locked. The safety member 85, when in the " safe " position, also locks the toggle link 24 to the breech-block 23, preventing the opening of the breech and the lifting of the hook 84 from its locking position relatively to the striker and sear. The trigger 8 is pivoted to the receiver at 112 and engages with a rocking lever 115 pivoted at 116 and connected to an arm 104 and to one abutment of a spring 125, the other abutment of which is on a lug depending from the arm 104. The spring 125 thus acts to hold the trigger forward against a spring plunger 117, and the bar 104 up against a pin 127. The counterclockwise movement of the rocker 115 is limited by a fixed abutment 120, and the engagement between the rocker and the trigger is such as to produce a preliminary pull at long leverage and then a firing pull at quicker acting leverage. This last pull will cause the nose 104' of the bar 104 to bear on the tail 103 of the sear trip 81 and to push the sear trip forwards, thereby rocking the sear 71 and releasing the spring striker. When the toggle again closes the breech after the recoil due to the firing of a shot, the bevelled rear end 103 of the sear trip 81 comes over the nose 104' of the bar 104 and depresses that bar unless the trigger has been released. Thus only one shot can be fired at a time. The trigger must then be released to enable the bar 104 to retract and spring its nose 104<1> up again behind the rear end 103 of the sear trip 81, after which the mechanism is ready to fire a fresh shot. The opening of the toggle lifts the end 103 of the sear trip out of line with the nose 104<1> of the bar 104, so that the striker cannot then be released by any accidental pull on the trigger. The various parts of the mechanism are made in such a way as to facilitate assembling and disassembling. The barrel is attached to the front end of the stock by two band clamps and is provided with a hand guard or cover 12. The Specification also describes parts of the cartridge loading and feeding devices and means for holding the breech-block in the retracted position when the magazine is empty forming the subject-matter of Specifications 291,779, 291,780, and 291,781.