My friend who is a welder, machinist, jack of all trades, built a spin target out of 3/4 steel. He shot the target with 22's that did nothing of course, a Henry .44 mag lever action rifle that dented the steel a little, a 30-30 that did little damage to it, but the 50 caliber muzzleloader really put a dent into those plates. I believe they were shooting very close thought. And that one from sportsman's guide say 100 yards minimum range. So that might account for why my friends took such a beating.

I have steel plates in my bullet trap. I have yet to break one or shoot through one, but you can see the muzzle loader marks on them real plain.