ABSTRACT
The cartridge case contains the propellant explosive, which is ignited by the primer in the base of the case. Large calibre fixed round cartridge cases are usually made in 70/30 brass. Tensile testing of cartridge brass specimens is done after fully annealed material is put through a rolling mill at room temperature, and after 50% cold rolled specimens have been heat treated in furnaces set at various temperatures. As an alternative to cold deep drawing, brass or mild steel cartridge cases can be made by spiral wrapping cold rolled sheet (like a toilet roll tube) followed by seam welding and welding to the separate base. A brass disc, intermediate cup, and finished 105 mm case are photographed in particular Plate. It is perhaps surprising that all calibres of fixed round cartridge cases have an intentional hardness gradient along their length – as sketched right, and photographed in particular Plate.
