Method of making polymer ammunition cartridge having a two-piece primer insert

1. A method of making polymer ammunition having a two-piece primer insert comprising by the steps of:

providing a two piece primer insert comprising: an upper primer insert portion connected to a lower primer insert portion, wherein the upper primer insert portion comprises an upper primer bottom surface and an upper primer top surface opposite the upper primer bottom surface, an upper primer aperture through the upper primer bottom surface, a substantially cylindrical coupling element extending away from the upper primer bottom surface, wherein the lower primer insert comprises: a lower primer top surface opposite a lower primer bottom surface, a primer recess in the lower primer top surface that extends toward the lower primer bottom surface and adapted to fit a primer, a lower flash hole aperture through the lower primer bottom surface extending to the primer recess; and

providing a flash hole groove in the top surface of the upper primer insert portion, the flash hole groove extends circumferentially about the upper primer aperture and the flash hole groove is larger than the upper primer aperture, and wherein the flash hole groove is between the upper primer aperture and the lower flash hole aperture;

providing an insert joint linking the upper primer top surface and the lower primer bottom surface and the insert joint aligning the upper primer aperture with the lower primer aperture to form the two-piece insert;

providing a first polymer composition for molding a polymer ammunition cartridge;

molding from the first polymer composition a substantially cylindrical polymeric middle body having the primer insert at a first end and a substantially cylindrical polymeric coupling region at a second end, wherein the first polymer composition extends over an outer surface of the primer insert to a flange that extends circumferentially about an outer edge of the lower primer top surface and the first polymer composition extends over an interior surface of the substantially cylindrical coupling region into the flash hole groove to form a flash hole, wherein the first polymer composition extends from the substantially cylindrical polymeric coupling region into the flash hole groove;

forming a substantially cylindrical polymeric bullet-end component from a second polymer composition comprising a bullet aperture opposite a polymeric bullet-end coupling that mates to the substantially cylindrical coupling region;

coupling the substantially cylindrical coupling region to the polymeric bullet-end coupling to form a propellant chamber that extends from the flash hole to the bullet aperture;

inserting a primer into the primer recess, wherein the primer is in operable communication with the propellant chamber through the flash hole;

at least partially filling the propellant chamber with a propellant; and

frictionally fitting a projectile in the bullet-end aperture, wherein the propellant chamber is enclosed at one end by the primer and the projectile at the other end.

2. The method of claim 1 , wherein the insert joint is threaded, riveted, locked, friction fitted, coined, snap fitted, chemical bonded, chemical welded, soldered, smelted, sintered, adhesive bonded, laser welded, ultrasonic welded, friction spot welded, or friction stir welded.

3. The method of claim 1 , wherein the upper primer insert portion, the lower primer insert portion or both are formed independently by metal injection molding, polymer injection molding, stamping, milling, molding, machining, punching, fine blanking, smelting, or any other method that will form insert portions that may be joined together to form a primer insert.

4. The method of claim 1 , wherein the upper primer insert portion, the lower primer insert portion or both independently comprise a polymer, a metal, an alloy, or a ceramic alloy.

5. The method of claim 4 , wherein the upper primer insert portion and the lower primer insert portion comprise the same material or different materials.

6. The method of claim 1 , wherein the upper primer insert portion comprises a polymer, a metal, an alloy, or a ceramic alloy and the lower primer insert portion comprises a different polymer, metal, alloy, or ceramic alloy.

7. The method of claim 1 , wherein the upper primer insert portion and the lower primer insert portion comprise steel, nickel, chromium, copper, carbon, iron, stainless steel or brass.

8. The method of claim 1 , wherein the first polymer composition, the second polymer composition or both independently comprise a nylon polymer.

9. The method of claim 1 , wherein the first polymer composition, the second polymer composition or both independently comprise between about 10 and about 70 wt % glass fiber fillers, mineral fillers, or mixtures thereof.

10. The method of claim 1 , wherein the first polymer composition, the second polymer composition or both independently 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-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.

11. The method of claim 1 , wherein the bullet aperture comprises one or more cannelures formed on an inner circumferential surface of the bullet aperture.

12. The method of claim 1 , wherein the bullet aperture accepts a 0.221, 0.223, 0.243, 0.25-06, 0.264, 0.270, 0.300, 0.308, 0.338, 0.30-30, 0.30-06, 0.45-70 or 0.50-90, 50 caliber, 45 caliber, 380 caliber or 38 caliber, 5.56 mm, 6 mm, 7 mm, 7.62 mm, 8 mm, 9 mm, 10 mm, 12.7 mm, 14.5 mm, 14.7 mm, 20 mm, 25 mm, 30 mm, 40 mm, 57 mm, 60 mm, 75 mm, 76 mm, 81 mm, 90 mm, 100 mm, 105 mm, 106 mm, 115 mm, 120 mm, 122 mm, 125 mm, 130 mm, 152 mm, 155 mm, 165 mm, 175 mm, 203 mm or 460 mm, 4.2 inch or 8 inch projectile.

13. The method of claim 1 , wherein the projectile has a frustoconical shaped nose.

14. A method of making a polymer ammunition having a two-piece primer insert comprising by the steps of:

forming a two-piece primer insert comprising the steps of:

forming an upper primer insert portion comprising an upper primer bottom surface, an upper primer aperture through the upper primer bottom surface and an upper primer top surface opposite the upper primer bottom surface; a substantially cylindrical coupling element extending away from the upper primer bottom surface, and an interior surface inside the substantially cylindrical coupling element;

forming a lower primer insert portion comprising a lower primer bottom surface opposite a lower primer top surface, a primer recess in the lower primer top surface that extends toward the lower primer bottom surface and adapted to fit a primer, a lower primer aperture through the lower primer bottom surface, and a flange that extends circumferentially about an outer edge of the lower primer top surface;

forming a flash hole groove in the top surface of the upper primer insert portion, the flash hole groove extends circumferentially about the upper primer aperture and the flash hole groove is larger than the upper primer aperture, and wherein the flash hole groove is between the upper primer aperture and the lower flash hole aperture;

aligning the upper primer top surface and the lower primer bottom surface to form an insert joint and to align the upper primer aperture with the lower primer aperture;

linking the upper primer top surface and the lower primer bottom surface to form the two-piece primer insert;

providing a first polymer composition for molding a polymer ammunition cartridge;

molding from the first polymer composition a substantially cylindrical polymeric middle body having the primer insert at a first end and a substantially cylindrical polymeric coupling region at a second end, wherein the first polymer composition extends over an outer surface of the primer insert to the flange and extends over an interior surface of the substantially cylindrical coupling region into the primcr flash hole groove to form a flash hole, wherein the first polymer composition extends from the substantially cylindrical polymeric coupling region into the flash hole groove;

forming a substantially cylindrical polymeric bullet-end component from a second polymer composition comprising a bullet aperture opposite a polymeric bullet-end coupling that mates to the substantially cylindrical coupling region;

coupling the substantially cylindrical coupling region to the polymeric bullet-end coupling to form a propellant chamber that extends from the flash hole to the bullet aperture;

inserting the primer into the primer recess, wherein the primer is in operable communication with the propellant chamber through the flash hole;

at least partially filling the propellant chamber with a propellant; and

frictionally fitting a projectile in the bullet-end aperture, wherein the propellant chamber is enclosed at one end by the primer and the projectile at the other end.

15. The method of claim 14 , wherein the upper primer insert portion, the lower primer insert portion or both are independently formed by metal injection molding, polymer injection molding, stamping, milling, molding, machining, punching, fine blanking, smelting, or any other method that will form insert portions that may be joined together to form a primer insert.

16. The method of claim 14 , wherein the upper primer insert portion comprises a polymer, a metal, an alloy, or a ceramic alloy and the lower primer insert portion comprises a different polymer, metal, alloy, or ceramic alloy.