off occurs when a  very hot breach causes a round to fire by itself, not at all what  happened in this case. Secondly, a misfire is indeed dangerous  because you dont know if the primer was struck or the firing  mechanism failed. If the primer was struck, the round could still  fire unexpectedly. On rare occasions a primer can burn slowly for a  bit, then go off. The best place to be in that case is in the tank,  clear of the breach. (if the gun does fire the recoiling breach  could maim or kill you if you got in the way 