I was helping out at law enforcment firearms school yesterday and an instructor with some fairly impressive credentials was talking about the evolution of barrel twist rates in Colt AR-15 rifles. He said more than once that the 1:7 twist barrels were designed for bullets in the 62 to 80 grain weight class, and would not stabilize the 55 grain and lighter projectiles. Has anyone ever heard of a very fast twist causing a bullet to become unstable? I sure haven't. Roskoe