Patent GB-470250-A (GB)
Title: Improvements in projectiles or bullets
IPC: F42B14/02
Filed: 1935-12-11
Abstract: 470,250. Projectiles. COLEMAN, C. J. Dec. 11, 1935, Nos. 34333/35 and 22733/36. [Class 9 (i)] Pressure sealing means for a projectile or bullet comprises a plurality of smooth-faced rearwardly-directed annular flanges nested together with their adjacent surfaces in contact in such a manner that the pressure of the propellant when exploded acts upon the rear surface of the rearmost flange so as to urge the foremost flange or a part associated therewith into abutting or similar annular gastight relationship with a surface or surfaces on the projectile that maintains said flanges in a rotational plane at right-angles to the axis of the 'projectile, and to urge all the flanges into intimate sealing relationship with each other and one or more of them into intimate sealing contact with the interior of the gun barrel. Fig. 2 shows a construction in which a number of nested U-shaped copper rings c<1> are contained in a groove b<1> in the projectile a. If desired, alternate rings may be composed of asbestos &c., which may be impregnated with grease or graphite. The projectile may be adapted to engage the rifling in the barrel and the rings are distorted into said rifling to provide a seal, or, if the projectile does not engage the rifling, the rings may be cemented, as by cellulose cement, to the projectile and thereby communicate rotary motion from the rifling to it. According to modifications, the projectile may be provided with a number of grooves b<1> each containing a plurality of nested rings and each ring may be formed of two parts whose ends engage in lap joints so that, on leaving the gun, they are detached by centrifugal force and by the air-wash past the projectile. Fig. 5 shows a further construction in which the streamlined rear end h of a rifle bullet a<1> has mounted thereon a number of V-shaped rings c<4> which may be secured to the bullet by a temporary adhesive or held in place by the charge in the cartridge case d<1>. When the bullet is rotated solely by the engagement of the sealing means with the rifling, the inner flanges of the rings c<4> are provided with depressions or lugs which engage helical or longitudinal grooves in the end h of the bullet, whilst, in a further modification, Figs. 12 and 13 (not shown), the rings are replaced by cups having rearwardly-directed flanges that engage the gun barrel, the cups being provided with interengaging depressions that engage longitudinal grooves in the end of the bullet. Fig. 11 shows still a further modification in which the projectile a, which is furnished with the usual copper driving bands p, is provided with the flanged flat discs c<6> which may be secured to its flat rear end by a temporary adhesive or merely held in place by the charge. The sealing means, which may be cemented together by cellulose cement, may, in some cases, be formed of celluloid, slow-burning nitrocellulose, thin aluminium, magnesium or other material of such thickness, strength and perishability that it will sufficiently withstand the temperature and pressure when fired from a gun to effect the pressure seal and, where required, to rotate the bullet, but substantially to perish by burning or disintegration or both, shortly after leaving the gun.