heres a guess dan. im no scientist or ballistics expert so its all i can do is guess. I think in the case of the .50 soft points, they expanded into perfect mushrooms and were just to dammed big to allow good penetration. the 50 hps had a huge hp cavity probably even bigger in design then the lyman devestator. They were also cast out of ww. What i think with them is the lead was soft enough that they opened imediately and shed there noses real quickly. The quick opening no doubt made them lose velocity and what was left was about a 200 grain wadcutter. These bullets were holowpointed down into about half the lenght of the bullet and that much of it was gone. The devesators are an extream hp too and i dont in a minute beleive that because this one i shot at a buffalo penetrated the next one will too. As a matter of fact id bet my gun the ohter way. I think what helped it though was that it was cast slightly harder, out of #2 and it may have delayed expansion till the bullet cleared the hide as it did have a small enterance hole. Then about 1/3 of the bullet lenght is hped instead of 1/2 so after it lost its nose i still had a little bit better sectional density. its also a smaller bullet so its going to have less resistance. I allways thought that with a larger slug the extra weight compensated for this but i think when you get into the real big bores you are going to need much more retained weight to insure penatration. I never was one for believing in stuff that happened but didnt make sense but ive got to say in penatration testing the .475 about allways outdid the .500 even when you stepped up the bullet weight and velocity of a 500 to get the equivelent SD. Could be theres just some unknown (at least to me) barrier there that preventing it. I know that if you increase velocity most alloys dont hold up and if you increase weight enough to compensate you get into the the point that the 500 wont push them fast enough to be ideal without beating up yourself and your gun. I think John Linebaugh had it right (as usuall). these gun do there best work with flat nose hard cast bullets at moderate velocitys. He allways said if you want to really wack a 1000 lb or under animal use the 500 and if you want to reallly get serious with penetration on the big stuff use the .475. Seems like every time we test a new aspect of these big guns we come right back to what John allready figured out.