Theoptimum rate of twist for .223 bullets in the 50 to 55 grain weight range is probably a 1:14; no faster than a 1:12. However, 8" and 9" twist guns have provided good accuracy in many instances with light bullets. The main thing to remember about twist is that if you have too much, you very well may still be OK. If you don't have enough, however, you are absolutely out of luck. No exceptions.

The 9" twist will usually stabilize bullets up through the 75 Hornady A-Max. It is considered by many to be the most versatile of the AR-15 barrel twists. For the 77 and 80 VLD's you need at least an 8" twist.