Barrel Twists
223 Remington / 5.56 NATO rule of thumb.....
1:12 - 55 grain max, best with 50 grain or less
1:10 - 60 grain max, best with 55 grain or less
1:9 - 69/70 grain max, best with 65 grain or less
1:8 - 77 grain max, beat with 69/70 grain or less
1:7 - made pretty much for the 77 - 80 grain VLD bullets
With a fast twist (1:9 or faster) and a light (like 40 grain) bullet pushed to a high velocity (3700 fps+), depending on bullet construction, you can cause the bullet to self-destruct from centrifugal force.