I missed something...why is the lighter bullet retaining more energy? For two bullets of the same caliber, this will not usually be the case. Not only does the heavier bullet start out with more energy (unless you start it too slow) but if also similar shape it will retain energy better due to improved BC.

I've never had a problem with pass-thrus on whitetails. I think I've only had 2-3 total on dozens and dozens of deer 150yds or under. I need to shoot 200+ yds with 200gr bullets to have them stop in the deer with any frequency (10-20% of the time). This on broadside or quartering shots, it's easy to stop a 300gr bullet if you shoot them lengthwise through the front...