AR-15 Barrel Twist Rate: 1:7 vs 1:8

What twist rate means, and the twist of every One Horse AR-15 barrel in 5.56 NATO and .300 BLK.

Quick answer

Twist rate is the distance the bullet travels to make one full turn. All One Horse .300 BLK barrels are 1:7. One Horse 5.56 NATO barrels are 1:7, except the 16″ SOCOM mid-length, which is 1:8.

Twist chart

One Horse AR-15 barrel twist rates

Barrel	Caliber	Twist
7.5″ .300 BLK	.300 BLK	1:7
10.5″ .300 BLK	.300 BLK	1:7
16″ .300 BLK	.300 BLK	1:7
7.5″ 5.56	5.56 NATO	1:7
10.5″ 5.56	5.56 NATO	1:7
16″ 5.56 M4	5.56 NATO	1:7
16″ 5.56 SOCOM	5.56 NATO	1:8

Specs from the One Horse barrel product pages. Every One Horse barrel is 4150 steel.

The basics

What 1:7 and 1:8 mean

Twist rate is how far the bullet travels down the bore to make one full turn. A 1:7 barrel turns the bullet once every 7 inches; a 1:8 barrel turns it once every 8 inches. A lower number is a faster twist.

.300 BLK: always 1:7

All One Horse .300 BLK barrels are 1:7 twist, in 7.5″, 10.5″ and 16″. See them built into a complete upper on the 300 Blackout upper page, or compare calibers in 300 Blackout vs 5.56. Running a can? See the 300 Blackout suppressor (Ryn .30 cal), Ashe vs Ryn, how to buy a suppressor, and the suppressors hub.

5.56 NATO: 1:7, plus one 1:8

The 7.5″, 10.5″ and 16″ M4 5.56 NATO barrels are 1:7. The 16″ SOCOM mid-length barrel is 1:8. Chamber questions are covered in .223 vs 5.56. For a 5.56 can, see the Ashe 5.56 suppressor.

FAQ

Common questions

What twist rate are One Horse .300 BLK barrels?

All One Horse .300 BLK barrels are 1:7 twist, including the 7.5", 10.5" and 16" barrels.

What twist rate are One Horse 5.56 barrels?

The 7.5", 10.5" and 16" M4 5.56 NATO barrels are 1:7. The 16" SOCOM mid-length 5.56 NATO barrel is 1:8.

What does 1:7 twist mean?

The rifling turns the bullet one full revolution every 7 inches of barrel.

Is 1:7 faster than 1:8?

Yes. 1:7 makes one turn in a shorter distance, so it is the faster twist.

Questions? Email customerservice@theonehorse.com.