a training firearm that provides a realistic recoil effect . the firearm , preferably a pistol , may be an actual firearm retrofitted with a self - contained “ blow back ” assembly . usually , the pistol will include a laser device that emits a laser beam readable by a target system . the laser replaces live rounds , and the blow back assembly causes return of the slide to cycle in a manner similar to that caused by live ammunition in an unmodified weapon . the blow back assembly is driven by a disposable cartridge of compressed gas self - contained in the handle of the pistol . a valve integrated with the firing pin releases a burst of gas when the firing pin is impacted by the hammer . the gas pushes back the slide and recocks the hammer for the next “ round .” this system provides law enforcement and military personnel a realistic tool to develop recoil management and target re - acquisition skills .