connection sabot 3 is provided with a central bore 10 through which retardation charge 7 communicates with working space 2 in a manner known per se sabot 3 has a concave surface 11 which applies against the countermass and terminates circumferentially in a rim having an acute front edge 12 braking sleeve 5 is secured by a screwed ring 13 against being driven out the rear end of the tube is covered by a sealing foil 14 except for the area of the firing bore 10 a refractory thermally insulating damming layer 15 is provided between sabot 3 and countermass 4 to make sure that the countermass 4 will be set off exclusively through retardation charge 7 a slide layer 16 for example of an aluminum foil is provided around the countermass to prevent an ignition by friction at braking sleeve 5 particularly if a composite propellant comprising ammonium perchlorate or potassium perchlorate is employed uniformly spaced apart spacers for example styropore strips 17 are provided on the outer circumference of countermass 4 to ensure a centered position thereof in tube 1 upon igniting the propellant charge hot powder vapors pass through bore 10 in sabot 3 and ignite retardation charge 7 simultaneously the pressure built up in the working space 2 expels countermass 4 by means of sabot 3 out of tube 1 sabot 3 penetrates by its acute front edge 12 between braking sleeve 5 and the inside of the tube wall and is thus stopped the delay time of retardation charge 7 is chosen to delay the ignition by means of detonator 9 and primercord 8 and then the combustion of the countermass to an instant as far as possible remote in time from the ejection thereof from tube 1 that is delay charge.