It twists it exactly 1 time per 10" of distance traveled. Faster velocities can help- I have shot hyper speeds in a 1-8 twist barrel that the bullet said needed a 1-6 (sierra 95gr.) It works. But often Speed cant totally compensate for the force need and a faster twist will make your life simpler. My 1-8 6.5-284 wont stabilize some bullets created for a 1-8. The Berger 170gr .277 bullets I could never get to stabilize in a 1-8 and I was shooting them over 3300 fps. So I had velocity and twist- So patience and practice will find the right combo you are looking for- research is a good starting point- then see what happens with your rifle.