I've not been having the same issues as you guys have, although I haven't shot any of the 75 grain loads either. I've shot only the 90g MK's and 90g Fusions, and had good luck with both as far as accuracy. I've shot it with temperature in the 30's, and in the mid 80's so far. At about 60 degrees the factory FGMM is running right around 2600 fps out of the 18", my handholds at the same temp are running about 52 fps faster. I shot a 7 shot group with the handloads the other day that measured right around 1.5" spread at 200 yards. Also shot a group at 520 yards that had a spread of 4.875". I don't believe that the 1:7 twist is your issue with the 75's. The only problems I've had with any of the factory ammo was from the first case of FGMM that I bought was blowing primers, the second case, I've had no issues with pressure and I've been through about 160 rounds of those.