I can believe this. Velocity being the key, not necessarily caliber. From my own experience on 1/2" steel at 300 meters using a 30-06 versus a .300 RUM with same bullet (Nosler BT) the '06 left little more than a bullet smear, the .300 RUM left a 3/4" hole. Really opened my eyes on what the effect of 500 fps increase in velocity can have.