Polymer ammunition cartridge having a two-piece primer insert

An ammunition cartridge having a two piece primer insert comprising:

• 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, an upper primer aperture through the upper primer bottom surface, a substantially cylindrical coupling element extending away from the upper primer bottom surface, and an upper primer top surface configured to abut a lower primer bottom surface,
• wherein the lower primer insert portion comprises:
• a lower primer top surface opposite the 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, wherein the lower flash hole aperture is larger than the upper primer aperture;
• a polymeric middle body extending from a middle body coupling region over the two piece primer insert and into the lower flash hole aperture to form a flash hole, wherein the polymeric middle body comprises a first polymer;
• a polymeric nose portion comprising a nose coupler connected to the middle body coupling region, a shoulder extending from the nose coupler, a neck extending from the shoulder and a projectile aperture in the neck, wherein the nose portion comprises a second polymer;
• and
• a propellant chamber defined between the flash hole and the projectile aperture.