Abstract: Combustion gas cartridge for a gas internal combustion fastening device, comprising an external casing over which is crimped the edge of an internal cup beyond which an outlet end projects. The external casing is stepped and includes three longitudinal zones having different respective diameters, namely a first edge zone, a second bearing zone for the head of a crimping machine having a smaller diameter than that of the edge zone and a third zone having a diameter equal to or greater than that of the edge zone and forming an annular shoulder together with the second bearing zone for the crimping head.