Method of making a metal primer insert by injection molding

A method of making a substantially cylindrical insert by metal injection molding comprising the steps of:

• providing a primer insert injection mold to form a substantially cylindrical primer insert, wherein the primer insert mold comprises a top surface opposite a bottom surface and a substantially cylindrical coupling element that extends from the bottom surface, a primer recess in the top surface that extends toward the bottom surface, a primer flash aperture positioned in the primer recess to extend through the bottom surface, a flange that extends circumferentially about an outer edge of the top surface, wherein the flange is adapted to receive a polymer overmolding that covers an circumferential surface and the primer flash hole aperture to form a primer flash hole, and a flash hole groove that extends circumferentially about the primer flash aperture on the top surface in the primer recess;
• providing an injection molding feedstock comprising a powder and a first binding agent and a second binding agent, wherein the powder comprises a stainless steel powder, brass powder, alloy powder, ceramic alloys powder or a combination thereof;
• injection molding the injection molding feedstock into the primer insert injection mold to form a first substantially cylindrical primer insert having a first size;
• debinding the first substantially cylindrical primer insert to remove the first binding agent;
• and
• sintering the first substantially cylindrical metal primer insert to remove the second binding agent and form the substantially cylindrical primer insert having a second size, wherein the second size is about 10 percent to about 25 percent smaller than the first size.