Base insert for polymer ammunition cartridges

A high strength polymer-based cartridge casing comprising:

• a cartridge body, molded from a polymer, comprising:
• a first end having a mouth;
• and
• a second end opposite the first end;
• an outer sheath disposed proximate the second end;
• a lower bowl disposed proximate the outer sheath and having a hole therethrough;
• an insert, formed from at least one of a metal and metal alloy, comprising a front end and a back end, and further comprising:
• a rim disposed at the back end;
• a primer pocket disposed at and open along a portion of the back end and continuing partially toward the front end;
• a flash hole disposed forward of the primer pocket, in fluid communication with the primer pocket, and continuing partially toward the front end;
• and
• an overmolded area formed at the front end, opposite the rim, comprising:
• a basin formed on an inside of the overmolded area and disposed above the primer pocket;
• and
• a ring formed, at a bottom of the basin, on an inside of the overmolded area, and surrounding the flash hole, comprising a ring wall;
• wherein the ring prevents polymer from the lower bowl from flowing into the flash hole by stopping the polymer at the ring wall;
• wherein the second end of the cartridge body engages with the front end of the insert;
• wherein the outer sheath is disposed to an outside of the overmolded area;
• wherein the lower bowl is disposed inside of the overmolded area and in contact with the basin;
• and
• wherein the hole in the lower bowl is disposed around the ring wall.