Abstract: An engineered polymer center fire small or medium ammunition cartridge case and methods for manufacturing the same, wherein the engineered polymer material meets the internal & external ballistic standards set by the Sporting Arms and Ammunition Manufacturers Institute and military specifications for center fire rifle small or medium calibers of ammunition cartridges from 0.223 caliber to 30 mm caliber. The cartridge case may allow a projectile to snap into place in the cartridge case mouth after the case is primed and propellant powder is placed into the cartridge case during the cartridge loading process. The rifle cartridge case may be either a single-piece case suitable for use in pistols or a two-piece case suitable for use in rifles, and may be formed by either injection molding or an injection blow molding process. Injection blow molding allows a single piece design. Also disclosed are inventive engineered polymers for use in cartridges.

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.