As Jim mentioned... its not just the twist, but the way your throat is cut. A .308 just isn't very finicky about twist, but how long the throat is can make a difference how much powder you can stuff behind a 185+gr bullet.
So far a 1-12" twist works very well behind the new longer 155gr bullets such as the 154 Scenar, 155 Palma, & 155.5 Fullbore. From past experience it'll spin bullets up to and including 190s without much problem, possibly more. I'm not sure what everybody else has been using; I have another 1-12" on the way but I also have a 1-10" coming because I want to 'experiment' a little with heavier bullet weights.