Never stand behind the breach and always, always remember what the instructor with the missing end of a pinky finger said about slapping the breach closed with your palm so as to keep all of your pinky finger!
Oh, wait, this guy looked so focussed on the latter part of that statement that he forgot the first part.
Glad the fifty fell apart during practice and not during an ambush! The 76mm(?) vid I've seen before. If it didn't kill the guy he got a severe cardiac contusion and probably a few broken ribs. The gun certainly shouldn't have fired when the breach closed though. The other dudes did seem pretty ill prepared to help their fallen comrade. There are some crazy vids floating around......