I used to use 150gr Ballistic Tips for the smallish deer here in N.C.. I found the bullet would explode once it got through the on-side hide. This pretty much turned everything it came in contact with into red jello. The deer couldn't stand it and died on their feet. I was concerned about the chance encounter with the occasional "big" buck and changed to the 165gr pill. Ranges ran from 150-450yds with results the same through out those ranges.
I would think the 150gr core-lock ultra would hold together pretty good at .300WinMag velocities. I have never used them before and would do my usual trial and error method (if you have the time) before making a final decision.
Hope this helps. Johnny K.