Abstract: The present invention provides an improved weapon such as a rifle or a pistol including a system of levers that are displaceable laterally towards the front part of the weapon for operating structure for the intake and compression of the compression air used in the weapon. The barrel for the weapon is axially displaceable on a slide by utilizing the displacement of the piston for the intake and compression of air. Sealing structure is provided on the breach of the barrel in the form of a tablet-shaped packing that also insures the correct insertion of the ammunition.