Patent ID: 7610858

Claim:
An ammunition cartridge comprising: (1) a substantially cylindrical polymeric cartridge casing body defining a casing headspace, with an open projectile-end for receiving a projectile and an end opposing the projectile-end, said casing body comprising: (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 comprises a male or female coupling element; and (B) a cylindrical polymeric middle body component with opposing first and second ends, wherein said first end comprises a coupling element that is a mate for said projectile-end coupling element joining said first end of said middle body component to said second end of said bullet-end component, and wherein said second end of said middle body component is said end of said casing body opposite said projectile end, said second end of said middle body component comprising a male or female coupling element; (2) a cylindrical cartridge casing head-end component comprising an essentially closed base end with a primer hole opposite an open end comprising a coupling element that is a mate for said coupling element on said second end of said middle body component joining said open end of said head-end component to said second end of said middle body component; wherein said projectile-end of said bullet-end component comprises an opening having an inner diameter in which any one point has a smaller diameter than the diameter of said projectile; wherein said middle body component is formed from a material that is more ductile than the material from which said head-end component is formed but equal to or less than the ductility of the material from which said bullet-end component is formed; and wherein said polymeric bullet-end component is formed from a polymer having all of the following properties: Yield or tensile strength at −65° F.>10,000 psi Elongation-to-break at −65° F.>15% Yield or tensile strength at 73° F.>8,000 psi Elongation-to-break at 73° F.>50% Yield or tensile strength at 320° F.>4,000 psi Elongation-to-break at 320° F.>80%; and wherein said polymeric middle body component is formed from a polymer having all of the following properties: Yield or tensile strength at −65° F.>10,000 psi Yield or tensile strength at 73° F.>8,000 psi Yield or tensile strength at 320° F.>4,000 psi.