I have both a 270 WSM with a 7 1/2 twist barrel, standard saami specification. No additional freebore. And have a 6.8 Western With 7 1/2 twist as well. Primary bullets: 165 Nosler ABLR, 170 Berger Elite and 175 Sierra TGK using H4831sc powder. Their accuracy about the same, have been shooting them at 600 and 1000 yards. The 6.8 is a little more efficient, little less powder needed. Running the bullets about 3000 fps for best accuracy. One inch groups for the 165 Nosler at 200 yards and about inch and half for the 175 Sierra. Best so far with the 170 Berger is a three inch group. Still working on that load. Use Hodgdon information for reloading data. Should add, the 150 Nosler ABLR is not shooting as well as I thought it would 3" groups at 200 yards.