Design and method for the manufacture of polymer cartridge case rimfire small arms ammunition

Abstract

A rimfire cartridge case may comprise a cylindrical case body, a case head disposed at a first end of the cylindrical case body, and a case mouth disposed at a second end of the cylindrical case body. The case head may have a circumference greater than a circumference of the cylindrical case body. The case head may comprise a hollow envelope configured to contain a priming mixture. The case mouth may be configured to mechanically engage a projectile. The cylindrical case body and the case head may be integrally formed in a single piece from a polymer material to define a chamber configured to hold a propellant and to contain a pressure generated by the propellant when the propellant is ignited by the priming mixture. Also disclosed are inventive engineered polymers for use in cartridges.

We claim: 
     
         1 . A rimfire cartridge case comprising:
 a cylindrical case body;   a case head disposed at a first end of the cylindrical case body and having a circumference greater than a circumference of the cylindrical case body, the case head comprising a hollow envelope configured to contain a priming mixture; and   a case mouth disposed at a second end of the cylindrical case body and configured to mechanically engage a projectile;   wherein the cylindrical case body and the case head are integrally formed in a single piece from a polymer material to define a chamber configured to hold a propellant and to contain a pressure generated by the propellant when the propellant is ignited by the priming mixture.   
     
     
         2 . A rimfire cartridge comprising:
 the rimfire cartridge case of  claim 1 ;   the projectile disposed in the case mouth;   the propellant disposed in the chamber; and   the priming mixture disposed in the hollow envelope.   
     
     
         3 . The rimfire cartridge case of  claim 1 , wherein the cylindrical case body comprises a locking lip disposed on an inner surface of the cylindrical case body at the case mouth, the locking lip being configured to mate with a mating groove of the projectile. 
     
     
         4 . The rimfire cartridge case of  claim 1 , further comprising an adhesive disposed on an inner surface of the cylindrical case body at the case mouth. 
     
     
         5 . The rimfire cartridge case of  claim 1 , wherein the polymer material comprises a nano-composite material comprising a nylon base. 
     
     
         6 . The rimfire cartridge case of  claim 1 , wherein the polymer material is formed by polymerization of a nano-clay which is a member of the smectite class of layered silicate or platy minerals. 
     
     
         7 . The rimfire cartridge case of  claim 6 , wherein the nano-clay comprises alumino-silicate particles uniformly dispersed in a polymer matrix. 
     
     
         8 . The rimfire cartridge case of  claim 1 , wherein the single piece comprising the cylindrical case body and the case head is formed in an injection molding or a blow molding process. 
     
     
         9 . The rimfire cartridge case of  claim 1 , wherein the priming mixture comprises a wafer inserted in the hollow envelope. 
     
     
         10 . The rimfire cartridge case of  claim 1 , wherein the cartridge case meets or exceeds the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) specifications for the design of rimfire small arms ammunition cartridges. 
     
     
         11 . The rimfire cartridge case of  claim 1 , wherein the cartridge case meets or exceeds the Commission Internationale Permanente (CIP) specifications for the design of rimfire small arms ammunition cartridges. 
     
     
         12 . The rimfire cartridge case of  claim 1 , wherein the cartridge case is configured to be used for .22 short, .22 long, .22 long rifle, .22 Magnum, .22 Stinger, .22WRF, 5mm Remington Magnum, .17 Hornady Magnum, or .17 Hornady Mach 2 caliber ammunition. 
     
     
         13 . The rimfire cartridge case of  claim 1 , wherein the cylindrical case body is a straight walled cylinder. 
     
     
         14 . The rimfire cartridge case of  claim 1 , wherein the cylindrical case body includes a bottleneck.