I have a 7.7" CarbonSix 22" barrel in 22 Creedmoor. Just started loading development for it. If I had it to do over again I'd do an 8 twist. It seems like guys using fast twist 7" barrels are blowing up bullets. If you look into that people seems to think bullets need to stay under 290,000 RPMs. If you do the math a 7.7" can only push 88's at 3150fps. MV(12/twist rate) × 60 = RPM. I guess that means a 80gr bullet in an 8 twist can do 3200fps. 3200(12/8) x 60 = 288,000rpms.