AR-15 Barrel Buying Guide: Length, Twist Rate, Profile and Gas System

The barrel sets accuracy, weight and handling. Four choices matter most.

Length

16 inch barrels are a popular all around length. 14.5 inch barrels with a pinned muzzle device are shorter. 18 and 20 inch barrels give more velocity for longer shots. 10.5 to 12.5 inch barrels make compact rifles.

Twist Rate

1 in 7 stabilizes heavier bullets. 1 in 8 is a good balance for many bullet weights. 1 in 9 favors lighter bullets. Match twist to the ammo you shoot.

Profile

Lightweight and pencil profiles carry easily. Government profiles are common. Heavy profiles resist heat for longer strings of fire.

Gas System Length

The gas system length must match the barrel length and your handguard. Carbine, mid length and rifle lengths each run differently. See our gas system guide.

Materials and Coatings

Chrome moly vanadium and stainless steel are common. Nitride or chrome lining adds corrosion resistance.

Chambering

Barrel Fit and Install

A new barrel needs a proper headspace check and a correct torque on the barrel nut. A gunsmith can install it for you. Proper torque and a clean receiver face give better accuracy and avoid damage.

Break-In

Many shooters fire a small number of rounds, cleaning in between, though makers differ on break-in. Follow the instructions that come with the barrel. Use ammo your barrel is rated for, and avoid steel core rounds in barrels that do not allow them.

5.56 NATO chambers fire both 5.56 and .223. A .223 Wylde chamber is a mix. See the 5.56 AR build guide.