The very best one I saw, as the Range Conducting Officer was with a ruptured case. The front end of which was stuck in the breech. Anyway, firing point supervisor took non firing weapon off soldier, cocked gun, cleared(?) stoppage and then rammed home breech block AND new live round into already obstructed chamber using right thumb and fore-finger.
Live round aligned with recessed breech block due to excess force applied by dozy fart! Round fired while partially out of chamber. Blew thumb back breaking it at joint and sent shower of brass shrapnell into palm of hand. Ho, ho, ho.
He blamed gun and ammunition. I blamed idiot combined with Darwins theory of natural selection