THE ORB,
I'd suspect the barrel bedding. I always glass bed the action and the chamber area of the barrel, and free float the rest of the barrel channel. This always seems to do the trick. The most resent rifle I've been working on is a Remington M-700 BDL in .30-06. I've worked up a load of 59.5 grains of H-4350, CCI BR2 primers, Winchester cases and the 165 grain Sierra spitzer boattail. MV is 2830 fps. Five shot at a hundred yards, center to center, measure .247" from a benchrest. A very important benefit is that the bullet prints the same from a cold clean bore as it does from a warm dirty bore. Glassbedding may just be the cure to your problem. I hope that this is of some help. Good luck.