Multi-piece polymer ammunition cartridge

1. A polymeric ammunition cartridge having a 2 piece case comprising:

an primer insert comprising a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash hole aperture positioned in the primer recess to extend through the bottom surface, and a groove positioned around the primer flash hole aperture in the primer recess;

a polymeric middle body extending from a body coupling over at least a portion of the primer insert, wherein the polymeric middle body is molded over the cylindrical coupling element and into the primer flash hole aperture and into the groove to form a primer flash hole;

a polymer nose comprising

a generally cylindrical neck having a projectile aperture at a first end;

a shoulder comprising an outer shoulder surface that extends from the generally cylindrical neck to a shoulder bottom;

an inner shoulder surface on the inside of the polymer nose opposite the outer shoulder surface, wherein the inner shoulder surface is not parallel to the outer shoulder surface;

a side wall extending from the shoulder bottom; and

a nose junction positioned around the side wall, wherein the nose junction comprises a nose groove positioned around the side wall, and

a skirt connected circumferentially about the nose groove to extend away from the shoulder bottom, wherein the skirt is continuous with the inner shoulder surface and wherein an angle formed between the nose groove and the skirt is between 40 and 140 degrees and the nose groove and the skirt are adapted to mate to the body coupling wherein the skirt is adapted to not fit flush to the body coupling.

2. The polymer ammunition cartridge of claim 1 , wherein the nose junction is a groove and the skirt is positioned adjacent to the groove on the inside of the polymer nose.

3. The polymer ammunition cartridge of claim 1 , wherein an angle formed between the groove and the skirt is about 90 degrees.

4. The polymer ammunition cartridge of claim 1 , wherein an angle formed between the groove and the skirt is greater than 90 degrees.

5. The polymer ammunition cartridge of claim 1 , wherein an angle formed between the groove and the skirt is less than 90 degrees.

6. The polymer ammunition cartridge of claim 1 , wherein the polymer nose, the polymeric middle body or both individually comprise a nylon polymer, polycarbonate polymer, polybutylene polymer or a mixture thereof.

7. The polymer ammunition cartridge of claim 1 , wherein the polymer nose, the polymeric middle body or both individually comprise a fiber-reinforced polymeric composite.

8. The polymer ammunition cartridge of claim 1 , wherein the polymer nose, the polymeric middle body or both individually comprise between about 10 and about 70 wt % glass fiber fillers, mineral fillers, or mixtures thereof.

9. The polymer ammunition cartridge of claim 1 , wherein an adhesive groove is positioned in the projectile aperture.

10. The polymer ammunition cartridge of claim 1 , wherein the polymer nose, the polymeric middle body or both individually comprise a polymers selected from the group consisting of 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-butadinen-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.