Sierra bullets have tapered jackets that are thinner toward the front in order to give some semblance of controlled expansion. The few I have used on game (deer) have performed well enough that I have no complaints. I don't use them at magnum velocities!

One thing I have discovered, though, is that in most rifles I've tried this with, I can do my load development with Siera bullets, then switch to the same-weight Nosler Partition, and get the same results as far as velocity, accuracy, and point of impact. This does notwork with ALL rifles, but quite a few.For example, this 100 meter group was fired from a Argentine M1909, 7.65X53mm Mauser using both Sierra Game King and Nosler Partition 200-grain .308" bullets and the samecharge of IMR 4350. The relatively high MV is due to the 29" barrel!!