"The 1-12 is not good for the heavier bullets. I have seen a 1in group at 100yds with 55gr then switch to 60 and it opens up."
OK, your gun shot 55g with that particular load well, then you switched to the 60g and it opened up, which means that it did not like the 60g load. Do not confuse this with the twist rate because the 1-12 twist rate will stabilize every 60g Bullet made very well. The 65g Sierra is the most marginal of the ones that I listed for a 1-12 twist.
75g V max and in most rifles the 75g Hornady BTHP takes the 1-8 twist, but occasionally a rifle with a 1-9 twist will stabilize the 75g Hornady BTHP, occasionally.