Sierra Game Kings, Bullet seperation

We went hunting last weekend, used 308 180gr sierra point, core separation and fragmentation occurred on all the animal I shot. Loosing a large amount of meat on each animal. Found out friends experienced the same problem 3 weeks ago, loosing out on 6 blesbuck shot, their meat loss was just as bad. They contacted Sierra USA on-line, and they said it was the angle they shot at and bone fragmentation, when I e-mailed them 2 weeks later the same \ballistics engineer"said he had never heard of something like this. And we have the e-mails to prove it<br> .<br> He does not even want to give us any solid and conclusive answers"