I don't know the grade of steel used on the targets we were shooting. The lead slugs hit hard, but don't do any real damage to the steel. We shot a match where a shot on steel at less than 30 yards with a slug resulted in a DQ. It was a stage where the shooter had to use both slugs and shot, and 8 shooters made the mistake of the wrong ammo on the right target. No one hurt, but the targets had some obvious impressions from the slugs. No dents though. (3/8" plate) Best I can offer though.