Variable inside shoulder polymer cartridge

A method of making a high strength polymer-based cartridge casing comprising the steps of:

• molding a component using a polymer, comprising:
• a first end having a mouth;
• and
• a second end opposite the first end;
• molding a neck extending away from the mouth;
• molding a shoulder extending below the neck and away from the first end, and molding a propellant chamber extending below the shoulder, opposite the neck, wherein molding the shoulder comprises the steps of:
• forming an outside shoulder sloped at an outside shoulder angle in relation to a center axis extending longitudinally along the cartridge and passing through a center of the mouth;
• forming an inside shoulder sloped at an inside shoulder angle in relation to the center axis, and separated from the outside shoulder by a shoulder thickness which varies along the length of the shoulder, and uniform over a circumference of the cartridge casing;
• and
• shaping the inside shoulder to a concave shape, and
• wherein molding the neck includes the steps of:
• forming the neck to allow a projectile to extend into the propellant chamber past a portion of the inside shoulder, and creating uniform inside diameter from the mouth to the inside shoulder.

A high strength polymer-based cartridge casing inclosing a volume, comprising:

• a first end having a mouth;
• a neck extending away from the mouth;
• a shoulder extending below the neck and away from the first end, and
• a propellant chamber extending below the shoulder, opposite the neck;
• wherein the shoulder comprises:
• an outside shoulder sloped at an outside shoulder angle in relation to a center axis extending longitudinally along the cartridge and passing through a center of the mouth,
• an inside shoulder shaped convex, and separated from the outside shoulder by a shoulder thickness,
• wherein the shoulder thickness varies along the length of the shoulder, wherein the neck permits a base of a projectile to extend into the propellant chamber past at least a portion of the inside shoulder.

A method of making a high strength polymer-based cartridge casing comprising the steps of:

• molding a component using a polymer, comprising:
• a first end having a mouth;
• and a second end opposite the first end;
• molding a neck extending away from the mouth, comprising a inside neck wall and an outside neck wall;
• molding a shoulder extending below the neck and away from the first end, and
• molding a propellant chamber extending below the shoulder, opposite the neck,
• wherein molding the shoulder comprises the steps of:
• forming an outside shoulder sloped at an outside shoulder angle in relation to a center axis extending longitudinally along the cartridge and passing through a center of the mouth;
• forming an inside shoulder sloped at an inside shoulder angle in relation to the center axis, and separated from the outside shoulder by a shoulder thickness which varies along the length of the shoulder, and uniform over a circumference of the cartridge casing;
• and
• shaping the inside shoulder to a convex shape, and
• wherein molding the neck includes the step of forming the neck to allow a projectile to extend into the propellant chamber past a portion of the inside shoulder.