Abstract: A two component cartridge case which may be of dissimilar materials including a tubular casing component with a mouth for receiving a projectile and reduced diameter shank with male threads to be received by the base component with corresponding female threads, recessed pocket on its centerline for holding a primer and a flange for engaging a firearm extraction mechanism.The components, both tubular casing and base, are carefully proportioned to allow only a minimum of the base to enter a sizing die during sizing operations thus permitting ease of sizing using conventional (ordinary) sizing dies, while using a hard material in the base component for added strength.The components are shaped to permit manufacture of the tubular casing component from existing conventional cartridge cases or from specially headed two diameter cartridge cases.