Brent,
The reason I didn't mention bullet instability as a possible cause was that the standard twist in the .300 Savage is 1-10, which is far more than needed to stabilize a 150-grain Ballistic Tip. Sierra twist calculator suggests a 1-14 twist is sufficient, and the Miller Formula (the best I've encountered) says that a 1-10 will provide a stability factor of over 2, and 1.4 is considered plenty.
