Thread: Fast twist barrels

The principal factors affecting velocity variations with an identical load in different rifles are barrel length, bore diameter and chamber dimensions. Twist rate is not a factor but is required for stabilisation of various bullet weights. The standard .223 twist is 1-12" which is designed for the 55 grain bullet, 1-9" for 62 grain, 1-8" for 68-69 grain, 1-7" for 69-77 grain. You will find an overlap of performance in practice but those are the optimum rates for gyroscopic stability. I was getting sub 0.5 MOA performance from my 1-7" Ranger AR with 69 grain BTHP Sierras until Jacinda got it. My replacement 1-8" Tikka CTR gives 0.6 MOA with the same load - still good enough for 350 metre rabbits!