Patent GB-825226-A (GB)
Title: Improvements in or relating to cartridge and cartridge firing apparatus
IPC: F42B5/32
Filed: 1956-08-22
Abstract: 825,226. Cartridge-operated tools and ammunition therefor. OLIN MATHIESON CHEMICAL CORPORATION. Aug. 22, 1956 [Aug. 29, 1955], No. 25632/56. Classes 9(1) and 119 Apparatus for firing a rimless cartridge comprises a barrel a breech block, a cartridge chamber and a firing pin, the breech block having an axial bore extending from a recess which forms part of the cartridge chamber and a slidable element in the bore projecting into a head cavity of a cartridge in the chamber to support the cartridge. The barrel 21 closed by the breech block 23 has a counter-bore housing the forward end of the case 1. The rod 37 extending into the recessed head 5 of the cartridge serves as an anvil for the radial striker 47 and to eject the spent cartridge. Movement of the rod 37 is limited by engagement of a collar 39 with shoulders 43, 45 of the block 23. Fig. 9 shows a firing tool having a holder 51 for the breech block integral with a handgrip 53, and a housing 55 for a barrel 57. The housing 55 has an enlarged end in which is an axially movable sleeve 59 surrounding the barrel and stressed by a spring 61 so that a shield 63 carried by the sleeve is biased forwardly from the barrel. A flange 65 engages a removable key 67 to limit the outward movement of the sleeve. Vents 69 for propellant gases may be provided in the barrel, which is slidably mounted in the sleeve 59 and is surrounder by a collar 73 from which projects a handle 75 having a lost motion connection with the barrel. The barrel when retracted abuts the breech block 85, full retraction being obtained when the muzzle is pressed against the work surface. By operating the handle 75 the breech is opened to extract spent cartridges and reload the tool. Axial movement of the push-rod 93 is limited by a flange 99 against which bears a spring 101 to push the flange against a cap 103 held in place by a lock-nut 105. The firing pin 111 carried by a plunger 115 is housed in a cylinder 113 mounted in the grip 53, the plunger being held away from the cartridge by a spring 123. To fire the cartridge, a trigger 129 is pulled which operates a pawl 131 to stress a spring 125 surrounding an extension of the plunger 115 the pawl being rocked clear of the path of the plunger by co-operating surfaces 133, 139. When the trigger is released the spring 125 drives the firing pin against the cartridge and the pawl returns to its original position. Depending from the plunger is a stem 161 which bears against a hook 167 pivoted in a recess in the grip and stressed by a spring to prevent retraction of the plunger. This safety device is unlocked by inward movement of a lever 169 which must be held in the depressed position while the trigger is operated, the stem 161 having grooves engaged by the hook 167 unless the lever is depressed. An additional safety means is provided beneath the breech block consisting of a plate 173 slidably mounted and having a rear portion extending through a slot in the housing 113 to obstruct the breech block it pushes the plate clear of the housing 113. Instead of the plate, the apparatus may be arranged so that the cartridge is loaded into a position forward of the firing pin, being pushed to the firing position by the retraction of the barrel when pressed against the work-piece. To modify the driving force on the projectile or fastener F a bleed-off may be provided from the cartridge chamber as in Fig. 12. The push-rod is provided with a threaded passage 213 tapering to a bleed-off port extending through the nose of the rod. A threaded plug 217 adjustable longitudinally of the passage closes the bleed-off. By changing the position of the plug the volume of the exhaust chamber can be varied. The passage 213 may also be in the form of a valve or the propellant gases may be bled-off through a right-angled passage in the breech block. The apparatus may have an electric firing system, Fig. 29, in which the push rod is replaced by a pin 46J extending through an elector 37J and surrounded by insulating material 48J. As the breech is closed the pin is driven through the base wad WB of the cartridge to complete an electric circuit through the primer F. Cartridge.-The cartridge may be bottlenecked or have a flared mouth engaging the head of the fastener. Within the cartridge is a wad W of inflammable material, Fig. 2, overlying the propellant C. Preferably the head portion is tapered and recessed, the base of the recess being integral with the cartridge wall or closed by a wad WB. The annular space surrounding the recess contains the primer P, which is preferably moulded as a ring before insertion or may be a paste dried in situ. The cartridge wall around the recess is somewhat thinner than in the main body. In Fig. 20 the primer is not supported by an inner wall. Fig. 22 shows a cartridge symmetrically recessed at both ends, with the primer supported at the centre by an anvil 5F in the form of an axially perforated spool. The primer may also be arranged as an annulus in the mouth of the case and surrounding the head of the fastener F. Brass and other metals, cardboard or synthetic plastic materials may be used to make the case.