And there may have been different ammo used. Brandon mentioned “ballistic tips.” If he meant Nosler Ballistic Tips, they’re highly frangible.
I think YOU hit in most reasonable explanation.
Your freeper name is perfect
True. I tried to load some 150gr Nosler B-tips for my .30-30 Win. Accurate, and the results on wild hog were satisfying. LOA meant I could only chamber one at a time, but they still worked well.
SP, B-tip, hollow point, pre-franged... All designed to transfer more energy from the moving projectile to the target. The results on the ballistic dummy were impressive, but as you correctly stated, not necessarily apples=apples to what the SS were shooting.