Re: Sierra Pro Hunter Hunting Bullets
In almost all cases, they're exactly the same as the SGKs, differing only in the BT where the SPH are FB designs. Otherwise, same jackets (exactly) same core material, etc.. The Pro Hunters are usually a bit better than the SGKs about core/jacket separations, but again, that's sort of the nature of the design. With the exception of their 30-30 bullets (which use a dual-tapered jacket design), there's really no mechanical locking mechanism to retain the core upon impact.
If your rifle is shooting the flat based bullets better, you may have a tight/loose spot (or spots) within the bore. This is one of the common problems we found when BT bullets (be they SMKs or SGKs) aren't shooting, but FB designs like the SPH are.