What is Rifle Twist?


Anyone who has spent any time researching or shopping for a brand new AR-15 has come across the question: Should I buy the 1:9 twist or is the 1:7 better?

At one point every one of us has asked, “What does twist even mean? ” Barrel twist refers to the rifling in the barrel of modern rifles making a full 360-degree rotation in a given length of inches.

For example, a 1:7 twist means the rifling makes one complete rotation for every seven inches of barrel. The first number will indicate how many rotations the bullet will make, the second number will indicate how much barrel length it will take to complete the indicated number of rotations.

Simply stated, barrel twist is rotations per length of the barrel in inches.

However, it is important to know not all ammunition shoots well in every twist ratio. A barrel with a 1:7 ratio tends to be too fast a twist for shorter bullets under 55 grains like most lightweight varmint ammunition. 1:7 twist barrels were originally designed for the military's use of the long M856 tracers since they were unable to be stabilized in the recommended 1:9 barrel. We recommend some of our Prvi Partizan .223 75 grain HPBT to get the best performance out of your 1:7 twist barrel.

1:9 and 1:10 twist barrels are middle of the road for .223 projectiles, and these are the most common barrel twist ratios on the market. These barrel twist rates are perfect for medium to short length bullets ranging in weight from 40 to 62 grains. Cheaper Than Dirt! suggest the Hornady .223 55 Grain TAP FPD ammunition for the 1:9 and 1:10 twist rates.

When it comes to short bullets that weigh 55 grains or less, a 1:12 twist is an excellent choice. The original M16 rifles were manufactured with the 1:12 twist ratio to be paired with the light, short bullets that were the general issue at the time. You might consider the Hornady .223 55 grain Z-Max ZombieMax ammunition if you are shooting a rifle with a slow twist like a 1:12.