Cool "Box Gun", Johnny! I have fired an Astra 911 (I think) Mauser-type machine pistol on full auto. Not controllable without the holster stock. First shot goes where you aimed it; rest go into stratosphere. Not easy to fire short bursts, either.
Many years after that experiment, I was told that the business of gangbangers "aiming" auto pistols "sideways" originally came from the Chinese' military method of keeping Mauser-type machine pistol bursts in the same county as the shooter.
According to my source, they taught holding the weapon sideways and letting the muzzle traverse "across" the target rather than having the muzzle rise up and above it. I have no idea if this works or if it is even the source of the stupid posture that television bad guys always seem to take with their "wondernines". Anybody know????