Most often then not, I get a question on the twist rate of AR-15 barrels (AR-10 is a completely different animal, and is not addressed here) and which twist should a client select. The answer depends totally on you and what you will be using the rifle for. But let's explore.
Common twist rates of AR-15 barrels are: 1 and 7, 1 and 8, 1 and 9. So what's the most optimal? Answer is as always, depending on what bullet grain you prefer to shoot.
AR-15 barrels come in different lengths, materials, treatments, to name a few. Barrel rifling which measures the twist rate is another factor to consider when choosing a barrel for your AR-15 build. It impacts the spin on the bullet as it travels down the barrel. So for example, 1:8 twist means a bullet will make one rotation per 8 inches of barrel length. So for a shorter pistol size 7" barrel, we would want 1:7 twist so the bullet will make one full rotation.
Most clients select a twist rate based on the weight of bullet they usually use. Rule of thumb goes for heavier grain bullets, choose a faster twist. In other words, 5.56/.223 bullet with a weight of 55-85 grain, will likely perform better with a faster twist such as 1:7. A lighter grain, such as 45, will likely outperform in longer twist, 1:9. 1:8 twist is probably the most versatile for gun enthusiasts who like to shoot a variety of different ammo.
Bottom line, there is no right or wrong answer but matching the right ammo to your barrel twist will help your AR-15 rifle to outperform!
