Breechblock mechanism for a gun

It is known to arrange a breech mechanism for a gun so as to be displaceable within a parallel guide arranged at a right angle to the bore axis of the gun barrel, and to bring a mushroom shaped head for obturation to the chamber in a partial circular arc. Due to the plurality of drive means for the mushroom head, complicated motion sequences result within the breechblock system which may lead to increased susceptibility to malfunction and do not permit high firing rates. Such a breech mechanism is not suitable or the use of a highly elastic obturator disposed in the gun barrel. The invention makes it possible to provide a wedge-shaped insert (12), which is to seal an elastic obturator (8) disposed at the end of the gun barrel (3), so as to be movable on a sloped slide face (10) of a breechblock (9) which is guided in parallel in the breech ring (5) and is movable transversely to the bore axis (2) of the gun barrel, and to utilize the movement of the breechblock (9) in a simple manner initially for the closing stroke and thereafter for the sealing stroke of the wedge-shaped insert (12) exclusively in the direction of the bore axis. Since the sealing stroke takes place exclusively in the direction of the bore axis (2), it is possible to realize a uniform and defined tension in the obturator (8).