US Patent 11448490 Two-piece primer insert for polymer ammunition

The present invention provides a multi piece primer insert for ammunition 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, and a substantially cylindrical coupling element extending away from the upper primer bottom surface, wherein the lower primer insert portion comprises: 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 flash hole aperture through the lower primer bottom surface, wherein the lower flash hole aperture is about the same diameter as the upper primer aperture; a middle flash hole aperture positioned between the upper primer aperture and the lower flash hole aperture, wherein the middle flash hole aperture has a diameter greater than the lower flash hole aperture at the junction of the upper primer insert portion the lower primer insert portion.