Method of making a primer insert for use in polymer ammunition
View Patent ↗One embodiment of the present invention provides a polymeric ammunition cartridge and methods of making and using the same. The cartridge includes a substantially cylindrical insert connected to a substantially cylindrical polymeric middle body. The substantially cylindrical insert includes 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 positioned in the primer recess to extend through the bottom surface, and a flange that extends circumferentially about an outer edge of the top surface. The substantially cylindrical polymeric middle body includes a substantially cylindrical polymeric bullet-end and a substantially cylindrical polymeric coupling end connected by a powder chamber, wherein the substantially cylindrical polymeric coupling end extends over the substantially cylindrical coupling element and covers a circumferential surface of the primer flash hole.
1. A method of making a metal primer insert for a polymeric ammunition cartridge comprising the steps of:
providing an insert blank for machining;
machining a top surface on the insert blank;
machining a flange that extends circumferentially about an outer edge of the top surface;
machining an outer channel adjacent to the flange that extends circumferentially about the insert blank, wherein the outer channel is adapted to receive a polymer overmolding;
machining a substantially cylindrical coupling element that extends from the outer channel to a coupling tip, wherein the substantially cylindrical coupling element includes an inner coupling element surface that extends from the coupling tip to a bottom surface, wherein the bottom surface is opposite the top surface, wherein the substantially cylindrical coupling element is adapted to receive the polymer overmolding;
machining a primer recess in the top surface that extends toward the bottom surface;
machining a primer flash aperture in the primer recess through the bottom surface; and
machining a groove in the primer recess around the primer flash aperture adapted to receive the polymer overmolding.
2. The method of claim 1 , wherein the primer flash aperture is larger than a flash hole in a metal ammunition cartridge of the same caliber.
3. The method of claim 1 , wherein the primer flash aperture is larger than a flash hole in a metal ammunition cartridge of the same caliber to allow polymer overmolding into the primer flash aperture.
4. The method of claim 1 , wherein the metal primer insert is a 5.56 mm, 7.62 mm, .223, 308, 338, 3030, 3006, and .50 caliber primer insert.
5. The method of claim 1 , wherein the metal primer insert is a 380 caliber, 38 caliber, 9 mm, 10 mm, 20 mm, 25 mm, 30 mm, 40 mm, 45 caliber and the like.
6. The method of claim 1 , wherein the insert blank is a metal, an alloy, or a ceramic alloy.
7. The method of claim 1 , wherein the insert blank is stainless steel or brass.
8. The method of claim 1 , wherein the insert blank is a 102, 174, 201, 202, 300, 302, 303, 304, 308, 309, 316, 316L, 316Ti, 321, 405, 408, 409, 410, 415, 416, 416R, 420, 430, 439, 440, 446 or 601-665 grade stainless steel.
9. The method of claim 1 , wherein the insert blank is a Ti6Al4V.