Abstract: The plug for shotgun or rifle barrel using black powder is outstanding in that it has a means (2) likely to extract the primer (a) destined to ignite the black powder contained in a chamber (c) of the said plug (1), when the arm is being opened.

Abstract: An interchangeable trigger device comprising a standard trigger plate, allowing indifferently the mounting of a single selective trigger or of separate triggers. The plate comprises a flat base which can be fitted by pivoting into the opening of the receiver tang and a boss (1c) with a front lug (1d) to co-operate with the rear part of a double-acting sliding bolt (22), the front of which (22a) co-operates with the breech (23) when closing the gun; a top lever (14) actuating the sliding bolt (22) through an eccentric, for sliding it longitudinally according to three positions, a pivoting lever (24) with front stepped notches, and a double-acting elastic return means co-operating with the front nose of the bolt (22) for maintaining it in these positions.