I was in a room where a Sergeant let the slide slip on his .45 without dropping the magazine. It happened while he was "clearing" it to turn into the Arms room. The room itself had about 20 guys in it lining up to turn in machine guns and the like. It was pure luck that nobody was hurt. As it was, the round was dug out of the wall the next day after it had done two ricochets off the floor and another wall.
Part of the Sergeant's punishment was to go around to every squad of every platoon in the battalion and demonstrate the proper way to clear a .45 while pointing it into a barrel of sand that he had to transport himself.
I recall the story of the .45 pinwheel as the 1911 was hung through the trigger guard on the hook of a toilet stall...and proceeded to discharge until the magazine was empty.