Patent GB-190810418-A (GB)
Title: Improvements in Machine Guns.
Inventor: DYMOND GEORGE CECIL
Filed: 1908-05-13
Granted: 1909-07-13
Abstract: 10,418. Dymond, G. C., [McClean Arms and Ordnance Co.]. May 13. Machine guns; sights.-In a gasoperated gun of the kind described in Specification No. 10,021, A.D. 1908, the breech-bolt 68 is formed with interrupted screwthreads 71, which, in the locked position, engage with corresponding threads in a receiver 2. The operating- " slide " 37 of the motor piston 38 has a lug 51 which extends through a cam-slot in the underside of the. breech-bolt and carries the firing-pin, so that when the motor piston is driven rearwards at each discharge of the gun, it will first retract the firing- pin and then unlock and withdraw the breech - bolt. The gun-frame is formed with a platform 14 with cylindrical walls 17 to receive a removable and rotatable cartridge box or magazine 91 which is divided by radial vertical walls 92 into a series of compartments and has at its centre a non- rotating cylinder 95 formed with a spiral groove 94 to guide the bullet ends of the cartridges. The mechanism for imparting a step-by-step rotation to the magazine for feeding the cartridges to the breech of the gun comprises a bell-crank lever 60, of which one arm 80 carries a feed-pawl 81 engaging teeth 83 on the underside of the cartridge box, and the other arm 78, by means of a pin 59, engages a cam-groove 55 on the side of the operating-slide. The lever 60 is pivoted upon a door 29, which is hinged at 157 to the gun-frame, and carries an abutment 67, Fig. 10, for the rear support 41 of the mainspring 40. The movement of the cartridge box is limited by a lever 85 also pivoted to the door, which, as the lever 60 is rocked by the rearward motion of the operating-slide to rotate the cartridge box, is pressed upwards by a spring and projects into the path of the tooth 83 engaged by the pawl 81. On the return movement, a lug 89 on the lever 60 presses the tail of the lever 85 upwards and withdraws the stop. A spring-pressed pawl is also provided to prevent backward rotation of the magazine. The opening 15 between the magazine and the breech of the gun is normally closed by a slide 104, pressed forward into the position shown in Fig. 15 by a spring contained in a casing 107. A safety lever 111, pivoted upon the underside of the platform 14, locks the slide 104 in this position when the gun is not in use; but when the lever is turned into the inoperative position, it allows the slide to be forced aside by the following cartridge in the magazine. The slide 104 thus acts also as a brake to the rotation of the magazine. The cartridge is hold by wings 7 in position to be engaged by the breechbolt during the closing of the breech. The magazines 91, which are made of cheap material, are loaded at the cartridge factory and serve as packages for transporting the cartridges. The Specification also describes the following details, which do not however form part of the invention : (a) A firing-mechanism for firing automatically or single shots, comprising a sear 112 under the control of two triggers 120, 121 mounted side by side but in such a manner that the trigger 120, if pulled and held, keeps the sear depressed so that the gun fires automatically ; while on the other hand for single shot firing, the trigger 121 is hung upon a pin 126 and has an inclined face 129 which co-operates with a fixed pin 130, so that when this trigger is pulled, it is caused to move rearwards and is disengaged from the sear. (b) A cocking-slide 32, 33 mounted in a longitudinal bore 30 in the gun-casing 4 and provided with a finger 35 which projects through a slot 31 and engages with the lug 51 on the operating - slide 37. (c) A downwardly - inclined side 64, Fig. 15, formed on the operating-slide 37 for guiding the extracted cartridge case to the outlet 36. (d) A water-jacket 19 for the gun barrel 1, with a ball valve 154 at each end and an emptying- plug 156. (e) .A vertical rear-sight support 131 formed in the gun casing 4, the sight being elevated and traversed by screw mechanism as shown. (f) A perforated muzzle-attachment 141 for reducing the recoil ; and (g) a detachable shoulderpiece, the arm of which is adapted for use as a wrench and screwdriver for assembling and disassembling the gun.