Actually the clearing of firearms SOP is ... first to remove the
magazine. Second to point the weapon safely somewhere ( to prevent
ricochets also) and thirdly to cock and peer into the chamber to
check for rounds. Lastly, close the chamber and squeeze off in a
safe direction.
The guy who fired the blank cannot blame the magazine which he
should remove first. Secondly, by sighting the chamber, he should
have seen the blank stuck in there ( if there was one).
