The interesting thing about a big heavy bullet is that even if it's a bit frangible the pieces that break up still have enough mass to give decent wound potential. However, the other issue is that Sectional density wise the 325 grain .458 bullet is at .221, which might be a bit low. Even the 350 grain bullet is at only .238.
The .405 Winchester is often criticized as having low SD bullets with it's 300 grain versions going at .254. To reach this level 458 bullets have to weigh in at 375 grains.
Putting together low sectional density with a fast expanding flex tip design might limit penetration a bit too much....the low velocity of these rounds counters this somewhat. Love to see some extensive bullet testing but in the meantime I am sticking with 350 grain Hornady's as my minimum moose bullet in my own .450.
