One thing John Barsness has mentioned is that often the Ramshot spherical powders like TAC will give their best accuracy with magnum primers. Looks like that is consistent with baldhunter's group above. JB recently mentioned on one of the threads here that while switching to magnum primers does not always improve Ramshot accuracy, he had not ever had it make it worse.
I gave TAC a brief try in the .308 I am working with now with the 168 SMK, and only got 1.5-ish MOA. But I just checked my notes and saw I used a standard primer - I'll have to go back and try a magnum.
Heading to the range this morning with Big Game and Fed 215s under the 165 BT. Will report back here if I try TAC/magnum primer and it improves for me.
Rex
