Two-piece primer insert for polymer ammunition

A two piece primer insert for ammunition comprising:

• an upper primer insert portion comprising:
• an upper primer bottom surface opposite an upper primer top surface,
• a substantially cylindrical coupling element extending away from the upper primer bottom surface,
• a primer flash aperture penetrating the upper primer bottom surface, and
• a primer flash aperture groove positioned in the upper primer top surface around the primer flash aperture configured to receive a polymer overmolding through the primer flash aperture;
• a lower primer insert portion comprising:
• a lower primer bottom surface opposite a lower primer top surface, and
• a primer recess in the lower primer top surface that extends toward the lower primer bottom surface and adapted to fit a primer, and
• an insert joint that links the upper primer top surface and the lower primer bottom surface to align the primer flash aperture and the primer recess to form a primer insert.