AR-15 Barrel Twist Rate Explained

What is AR-15 twist rates?

How does it affect shooting accuracy? This AR-15-barrel twist rate blog will answer these questions and help you identify the best twist rate for your gun. When you're looking into improving your accuracy or range with an AR-15, someone will mention your twist rate at some point. 

What Is Barrel Twist Rate?

Bullets fired from guns made after the 19th-century spin/twist during flight. The spin boosts accuracy by enhancing a round's stability and aerodynamics.

Barrels make bullets spin with the help of grooves or rifling that line the inside of a barrel. Tighter or shorter grooves lead to a faster spin rate, while longer grooves cause a slower spin.

AR-15 rifling twist rate or barrel twist rate refers to the number of times a bullet spins per inch of barrel length. Example, a 1:8 twist rate means a round will complete a spin once every 8 inches as it travels through a barrel.

If you have a 16-inch barrel with a 1:8 twist rate, the bullet will complete a spin twice before exiting the muzzle. An 18-inch barrel with a 1:6 twist rate will cause a bullet to spin three times before leaving the gun. The more twists a bullet can complete before leaving the barrel, the more stable the bullet will be when it exits the muzzle. 

How Much Does Twist Rate Matter?

A lower ratio of the twist rate, the more spin a bullet will have. For instance, the same bullet fired from a 1:6 barrel will spin faster than one from a 1:7 barrel.

Heavier and longer bullets require a faster and tighter twist rate for adequate flight stability and accuracy. That’s because these bullets are less aerodynamic, and the spin improves the bullet’s ability to overcome wind resistance and travel straight to reach a target. If you select the optimal twist rate for your ammo, you can look forward to better shooting accuracy and range.

Most used AR-15 Twist Rates

AR-15 twist rates typically vary between barrels, and the difference can be due to barrel length, rifling, and other factors. You can usually find a barrel’s twist rate listed under its features or specifications. Here are some of the most popular AR-15 barrel twist rates:

1:7

A 1:7 twist rate barrel is a favorite among target practice and combat shooters because it is effective for stabilizing long-range, modern bullets that weigh over 69 grains. The twist rate can also work with most rounds that weigh 55 to 70 grains. It is so effective for combat shooting that the U.S. military uses this twist rate in its M4, HK 416, and M16-A4 rifles.

You can get barrels between 6 and 24 inches with the 1:7 twist rate. The shorter barrels are suitable for close-range combat, while the longer barrels offer better velocity for long-range shooting.

1:8

Compared to other AR-15 twist rates, 1:8 is the most versatile. Barrels with this twist rate can work well with most ammo, offering sufficient stability to 70 to 90-grain bullets and preventing overspin in light rounds. While 1:8 twist rate barrels can fire most slugs with adequate accuracy, the best results occur when firing 60 to 80-grain bullets.

What's the Best AR-15 Twist Rate?

The best twist rate for an AR-15 will depend on various factors, such as your ammo type and how you intend to use your gun. As we’ve established, heavy and lightweight bullets require different rates of spin, but if you want a twist rate that works well with various bullet weights, we recommend 1:8. Which is commonly always what we use. 

Among all the AR-15 twist rates, 1:8 inches are the most versatile and multipurpose. Just check out various AR twist rate charts, and you'll see that the 1:8 twist rate handles most AR-15 loads well. 

While the 1:8 twist rate can handle most loads, it works best with 60 to 80-grain loads. If shooting light ammo, the 1:8 twist rate won’t cause the round to spin out of control and veer dramatically after traveling a few yards. The twist rate can also stabilize rounds that weigh up to 90 grains.

But, if you want the very best bullet stabilization and accuracy, we recommend using the twist rate recommended for your specific ammo.