Can't recall the specific show, but I've seen a TV murder mystery that featured the villain slipping live ammo into a prop gun on a movie set, to make the death of his victim appear to be an accident at the hand of another. The gun in question was an automatic pistol.
Prop auto pistols are made to function with blanks by inserting a plug into the bore that almost entirely blocks it, leaving a small hole for gas to escape, but raising the pressure in the chamber to adequate levels. Guns with a locking mechanism usually have it deactivated, as can be seen on all the movie Glocks that have the locking surface on the barrel ground off at an angle, plainly visible at the rear of the ejection port.
Were one to actually fire a live round in a prop automatic pistol, the only result would be the destruction of the gun, and possible injury to the shooter.
What made it so stupid was that the whole thing would have made perfect sense if they had just used a revolver.
