An assembly for the shooting of a non-lethal projectile, the assembly being connectable to the muzzle of a gas or shocking-purpose handgun releasing high-pressure gasses at firing wherein the assembly comprises: - a firing barrel with a cylindrical interior having an axis and a predetermined length; - a projectile magazine capable of storing and feeding a predetermined number of projectiles with circular cross section and made of a resilient material, said magazine comprises a projectile channel ending in a feeder opening (22, 30), wherein said feeder opening (22, 23) communicates with the interior of said firing barrel at a rear section thereof; - a sliding valve placed in a space defined between said handgun muzzle and said feeder opening (22, 30) is spring-biased along said axis of said firing barrel, wherein said valve comprises an axial thoroughgoing bore with a narrowing portion and a front face which is located Immediately behind said projectile after said projectile has been introduced through said feeder opening (22, 30) in a firing initial position, and in front of the projectile when being in said firing position the inner diameter of said firing barrel is slightly smaller than the diameter of said projectile, and during firing the pressure of the released gasses on said narrowing portion will push said valve axially in forward direction against a spring bias, and the pressing force provided by said front face of said valve and the pressing force of the gasses streaming through said central bore of said valve will act simultaneously and in the same direction on said projectile, and these forces will deform said projectile and push it in said narrowing portion of said firing barrel, and the associated forward movement of said valve will close said feeder opening (22, 30); and said gasses will shoot said deformed projectile out of said firing barrel. - a firing barrel with a cylindrical interior having an axis and a predetermined length; - a projectile magazine capable of storing and feeding a predetermined number of projectiles with circular cross section and made of a resilient material, said magazine comprises a projectile channel ending in a feeder opening (22, 30), wherein said feeder opening (22, 23) communicates with the interior of said firing barrel at a rear section thereof; - a sliding valve placed in a space defined between said handgun muzzle and said feeder opening (22, 30) is spring-biased along said axis of said firing barrel, wherein said valve comprises an axial thoroughgoing bore with a narrowing portion and a front face which is located Immediately behind said projectile after said projectile has been introduced through said feeder opening (22, 30) in a firing initial position, and in front of the projectile when being in said firing position the inner diameter of said firing barrel is slightly smaller than the diameter of said projectile, and during firing the pressure of the released gasses on said narrowing portion will push said valve axially in forward direction against a spring bias, and the pressing force provided by said front face of said valve and the pressing force of the gasses streaming through said central bore of said valve will act simultaneously and in the same direction on said projectile, and these forces will deform said projectile and push it in said narrowing portion of said firing barrel, and the associated forward movement of said valve will close said feeder opening (22, 30); and said gasses will shoot said deformed projectile out of said firing barrel.