Method of making a polymer ammunition cartridge

Abstract

One embodiment of the present invention provides a method of making a polymeric ammunition cartridge having wicking texturing about the projectile aperture.

What is claimed is: 
     
         1 . A method of making a polymeric ammunition cartridge comprising the steps of:
 molding a primer insert by injection molding by injecting a feed stock comprising one or more powders and one or more binders into the primer insert injection mold,   removing the primer insert from the primer insert injection mold,   removing the one or more binders from the primer insert and sintering the primer insert, wherein the primer insert comprising a top surface opposite a bottom surface and a coupling element that extends from the bottom surface, wherein the coupling element forms an outer surface opposite an inner circumferential surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash aperture positioned in the primer recess to extend through the bottom surface, a primer flash aperture groove positioned in the primer recess around the primer flash aperture, and a locking groove that extends circumferentially about the top surface;   molding from a first polymer composition a polymer ammunition cartridge by overmolding a polymeric middle body over the primer insert at a first end and a polymeric coupling region at a second end, wherein the first polymer composition is overmolded and extends over an outer surface of the primer insert to the flange and extends over an interior surface of the coupling region to the primer flash hole aperture, wherein the first polymer composition extends from the polymeric coupling region to the primer flash hole aperture and to the primer flash aperture groove to form a flash hole;   forming a polymeric projectile end component from a second polymer composition, wherein the polymeric projectile end comprises a projectile end coupling region that extends to a shoulder region that reduces to a neck region having a projectile aperture; and   coupling the projectile end coupling region to the polymeric coupling region to form a propellant chamber that extends from the primer flash hole aperture to the projectile aperture.   
     
     
         2 . The method of  claim 1 , wherein the injection molding includes polymer injection molding metal injection molding or both. 
     
     
         3 . The method of  claim 1 , wherein the injection molding includes metal injection molding. 
     
     
         4 . The method of  claim 1 , wherein the first polymer composition is the same as the second polymer composition. 
     
     
         5 . The method of  claim 1 , wherein the first polymer composition is a ductile polymer. 
     
     
         6 . The method of  claim 1 , wherein the first polymer composition, the second polymer composition or both comprise a nylon polymer. 
     
     
         7 . The method of  claim 1 , wherein the first polymer composition, the second polymer composition or both comprise a fiber-reinforced polymeric composite. 
     
     
         8 . The method of  claim 1 , wherein the first polymer composition, the second polymer composition or both comprise between about 10 and about 70 wt % glass fiber fillers, mineral fillers, or mixtures thereof. 
     
     
         9 . The method of  claim 1 , wherein the bullet aperture comprises one or more cannelures formed on an inner circumferential surface of the bullet aperture. 
     
     
         10 . The method of  claim 1 , wherein the substantially cylindrical coupling region and the polymeric bullet-end coupling are welded or bonded together. 
     
     
         11 . The method of  claim 1 , wherein the first polymer composition, the second polymer composition or both comprise polyurethane prepolymer, cellulose, fluoro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyether imide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene fluoride or thermoset polyurea elastomer, acrylics, homopolymers, acetates, copolymers, acrylonitrile butadiene-styrene, thermoplastic fluoro polymers, inomers, polyamides, polyamide-imides, polyacrylates, polyatherketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether imides, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes, polyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, styrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, polycarbonates, allyls, aminos, cyanates, epoxies, phenolics, unsaturated polyesters, bismaleimides, polyurethanes, silicones, vinylesters, urethane hybrids, polyphenylsulfones, copolymers of polyphenylsulfones with polyethersulfones or polysulfones, copolymers of poly-phenylsulfones with siloxanes, blends of polyphenylsulfones with polysiloxanes, poly(etherimide-siloxane) copolymers, blends of polyetherimides and polysiloxanes, and blends of polyetherimides and poly(etherimide-siloxane) copolymers. 
     
     
         12 . The method of  claim 1 , further comprising one or more internal structures in the neck to support a bullet. 
     
     
         13 . The method of  claim 1 , wherein the bullet aperture comprises one, two, three, or more annular rings that mate with one, two, three, or more corresponding annular grooves positioned on a bullet.