I just finished a new build. It's a 6mm Ackley Improved with a 1-8 twist. I originaly wanted to shoot 105s and 107s but the throat is a little short so, thinking that the longer bullets would eat up some case capacity, I tried some 75 Vmax and 75 Sierra HPs. The Sierras flew incredibly well. A guy that has a similar set-up was surprised that I could get a lighter bullet like a 75 to fly so well out of such a tight twist. I know a tighter twist robs a little speed but can you over-stabilize a lighter bullet to where it ruins accuracy??