and that's why you don't fire FMJ's at steel.
It really has nothing to do with that and more to do with distance.
+1. My club decided, after much time, effort, and research that a 50 cal at 100 yds or less was a catastrophe waiting to happen.
I've never shot any rifle at steel unless it was 100 yards or more, and that was only a .223.
I have no idea what the safe distance for a 50 bmg is, but it's got to be a long way, I'd imagine. Perhaps 500+
and that's why you don't fire FMJ's at steel.