Abstract: The projectile (1) comprises a head (3) and a tubular tail section (4) carrying fins (5). A piston (6) is fitted inside the tail section so as to form, with the walls of the latter, a closed combustion chamber containing a propellent charge (7). The launching means comprise a cylindrical launching rod (2) which is mounted on a support (12). The rod (2) is hollow and contains a percussion member comprising a percussion pin (14) fast with a percussion rod (13). For launching the projectile, the latter is positioned on the launching rod (2) so that the end of this rod is engaged in the opening of the tubular tail section (4). The free end of the tail section is then centered in relation to the launching rod (2). When the ends of the launching rod (2) and of the piston (6) then come into contact, a centering is likewise produced at this level, because of the cooperation between the guiding surfaces (2') and (6').