Abstract: Cartridge case (1), especially for a smooth bore gun, comprising three elements made of plastic, namely a tubular body (2) with an assembly end (2a) which tapers into the shape of a cone frustum, a base (3) which has a frustoconical bore (3a) with substantially the same vertex angle as the tapering end (2a) of the tubular body, to which it is matched in order to act as a housing, and a bottom piece (4) with a frustoconical external profile of substantially the same vertex angle as the tapering end (2a) of the tubular body, and as the bore (3a) of the base (3).