The smaller bullet is penetrating with the larger bullets because it has a smaller frontal surface area to resist penetration the larger bullet is going as deep or deeper because of kinetic energy from it's increased weight. Like Whit said though there are alot of variables and therefore nothing can be set in cement. The smaller bullet is more susceptible to deflection or being stopped once it enters the animal. I'm pretty much against light for caliber bullets. I have some 355 HC's I load for my 475's but only because they are accurate, fast and fun to shoot, but if I'm hunting with them I use 400gr XTP's and if I feel I ever "need" a hard cast I have 425's loaded. The 41 I rechambered wasn't because i didn't think it could kill an elk, I did it because I knew anything a 41 could do a 45LC could do better.

I won't be wronged. I won't be insulted. I won't be laid a-hand on. I don't do these things to other people, and I require the same from them. John Wayne-The Shootist