An ammunition
cartridge assembled from (1) a substantially cylindrical polymeric
cartridge casing body defining a casing headspace with an open
projectile-end and an end opposing the
projectile-end, wherein the casing body has (A) a substantially cylindrical injection molded polymeric bullet-end component with opposing first and second ends, the first end of which is the
projectile-end of the casing body and the second end has a male or female
coupling element; and (B) a cylindrical polymeric middle body component with opposing first and second ends, wherein the first end has a
coupling element that is a mate for the projectile-end
coupling element and joins the first end of the middle body component to the second end of the bullet-end component, and the second end is the end of the casing body opposite the projectile end and has a male or female coupling element; and (2) a cylindrical
cartridge casing head-end component with an essentially closed base end with a primer hole opposite an open end with a coupling element that is a mate for the coupling element on the second end of the middle body and joins the second end of the middle body component to the open end of the head-end component; wherein the middle body component is formed from a material more ductile than the material head-end component is formed from but equal or less ductile than the material the bullet-end component is formed from. Methods for assembling ammunition cartridges and ammunition cartridges having the headspace length larger than the corresponding headspace length of the chamber of the intended weapon measured at the same basic
diameter for the cartridge casing without being so large as to jam the weapon or otherwise interfere with its action are also disclosed.