Patent GB-789245-A (GB)
Title: Improvements in or relating to open chamber gun and ammunition therefor
IPC: F41A9/28
Filed: 1955-08-30
Abstract: 789,245. Smallarms and ammunition therefor. DARDICK CORPORATION. Aug. 30, 1955 [Sept. 3, 1954], No. 24900/55. Classes 9(1) and 119 In a revolver the rotary chamber drum 1, Figs. 1, 2 is provided with spaced open chambers 5 each running from end to end of the drum for radially receiving a round of ammunition- 12 from a magazine 46, the outer surface of the round when seated within and filling the open chamber constituting a continuation of the cylindrical surface of the drum and the cross-sectional shape of each chamber 5 and of the ammunition being non-circular and, as shown, being substantially an equilateral triangle with arcuate sides. The drum is rotatable in a breech frame 2 having an arcuate breech surface 11, Fig. 4, for closing off the open top of each chamber in the firing position, in which position the front end of the chamber opens into the barrel 9, Fig. 1 whilst the rear end is closed by a flat breech surface 14. The frame 2 supports a firing pin 16 and a hammer 17 actuated by a rod 19 slidable in the frame which is bifurcated to receive one end of the trigger 18, having an arcuate slot 22 receiving a pin 23 so that rearward movement of the trigger 18 moves the rod 19 forwards and brings the hammer to the cocked position shown in Fig. 1. The rod 19 carries a hammer spring 25 urging the hammer head against the firing pin. The drum axle 4 is provided with cam surfaces 28, one for each chamber 5 and a lever 29 slidably pivoted on a pin 30 on the frame 2 engages at one end the cam surface 28 and is connected at the other end by pin 23 and slot 32 to the trigger 18. Clockwise movement of the lever 29 is opposed by a return spring 34 so that for each full rearward movement of the trigger the drum is rotated through 120 degrees and the lever 29 snaps back to its starting position. As the lever 29 escapes from the cam surface 28, the rod 19 is no longer held by engagement of the pin 23 against the side of the slot 32 and is moved to the right by the spring 25 to release the hammer 17 and effect firing. The drum is locked in the firing position by a detent 35 actuated by a pin 41 on a pinion 42 engaging, a rack 43 on the rod 19. The magazine unit 46 forms the handle for the gun and comprises two compartments separated by a partition 48 having at its upper end a bifurcated clamp 49 with flanges 50 seated in grooves 51 in the frame 2 and can be readily detached for loading. The topmost round in either compartment enters the first empty chamber of the drum 1 which-comes opposite thereto and as shown the right hand compartment is first emptied and then feeding from the left-hand compartment starts. An ejecting lever 57, Fig. 1, is pivoted iri a slot 56 at the bottom of each chamber 5 and extends beyond the end of the drum into a well 58 in the frame 2, the well 58 being concentric with the drum shaft 3, but having a camming surface which depresses the end of the lever 57 as the drum is rotated by the trigger mechanism after firing and thus rejects the cartridge case from the chamber 5. The cartridge walls 13. Fig. 4, are reinforced at the corners and the bullet 60 of cylindrical contour is supported wholly within the interior of the cartridge case by means of a cylindrical sleeve 61 forming a jacket for the bullet and terminating at one end in an obturating flange 62 with a re-entrant skirt portion 63 slidably but gas-sealingly engaging the walls of the cartridge case. A primer unit 64 closes the other end of the case and has a primer 65 in co-axial alignment with the axis of the bullet 60. The sleeve 61 may be rifled internally for co-action witha rotating band on the bullet, such rifling being aligned with the barrel rifling.