One piece polymer ammunition cartridge having a primer insert and methods of making the same

A method of making a polymeric ammunition cartridge comprising the steps of:

• providing a polymer ammunition cartridge blank comprising an unformed top end connected to a cartridge bottom by a polymer middle body to form a propellant chamber, wherein the unformed top end comprises a nose end aperture, wherein the cartridge bottom comprises a primer insert comprising a top surface opposite a bottom surface and a 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 in the primer recess positioned around the flash hole aperture, wherein the middle body is overmolded through the primer flash hole aperture into the groove;
• providing a thermal form comprising a body segment extending to a shoulder segment that transitions to a neck segment that terminates at a tip segment end and a mandrel extendable into the neck segment at the tip segment end;
• heating the thermal form;
• inserting the unformed top end into the thermal form;
• extending the mandrel into the nose end aperture;
• contacting the unformed top end with the tip segment end to form a polymer ammunition cartridge having a shoulder connected to a neck, wherein the nose end aperture forms a projectile aperture;
• and
• removing the polymer ammunition cartridge from the thermal form.