That is why you put a stop on the muzzle - the red thing with a hole in it you might have seen or even used if you were in the military - so that enough pressur

That is why you put a stop on the muzzle - the red thing with a hole in it you might have seen or even used if you were in the military - so that enough pressure is built up to cycle the action. Another function of the stop is to catch any small bits of plastic from the blank rounds which might otherwise be ejected at eye-piercing speed.