Two-piece insert and/or flash tube for polymer ammunition cartridges

A high strength polymer-based cartridge casing comprising:

• an upper polymer component, molded from a polymer, comprising:
• a front end having a mouth;
• and
• at least a wall between the front end and a back end of the upper component opposite the front end;
• and
• an overlap portion extending from an intermediate end of the wall and terminating at the back end of the wall, wherein the overlap portion has a reduced thickness relative to thickness of the wall at the intermediate end;
• an upper insert having a first end and an opposing second end, comprising:
• an overlap portion engagement area disposed approximate the first end, wherein the overlap portion engagement area comprises an undermolded or an overmolded area configured to engage the overlap portion to join the upper polymer component and the upper insert;
• an insert engagement area disposed approximate to the second end;
• a lower insert, having a top end and a bottom end, comprising:
• an upper insert engagement area engaging with the insert engagement area;
• a rim and groove disposed around an outside of the lower insert;
• a primer pocket disposed inside the bottom end;
• and
• a flash hole, inside the lower insert and communicating between the primer pocket and upper polymer component,
• wherein the upper insert and the lower insert are made from a metal, an alloy of metals, or an alloy of a metal and a non-metal.