AR-15 Gas System Length: Pistol vs Carbine vs Mid-Length

The gas system on every One Horse barrel, and how it ties into your buffer.

Quick answer

Gas systems run pistol, carbine, mid-length and rifle, shortest to longest. One Horse .300 BLK barrels are pistol gas. 5.56 barrels are pistol gas at 7.5″, carbine gas at 10.5″ and 16″ M4, and mid-length on the 16″ SOCOM.

Gas chart

Gas system by One Horse barrel

Barrel	Caliber	Gas system
7.5″ .300 BLK	.300 BLK	Pistol
10.5″ .300 BLK	.300 BLK	Pistol
16″ .300 BLK	.300 BLK	Pistol
7.5″ 5.56	5.56 NATO	Pistol
10.5″ 5.56	5.56 NATO	Carbine
16″ 5.56 M4	5.56 NATO	Carbine
16″ 5.56 SOCOM	5.56 NATO	Mid-length

Specs from the One Horse barrel product pages.

The basics

Pistol, carbine and mid-length

Gas system length is where the gas port sits on the barrel, named from shortest to longest: pistol, carbine, mid-length and rifle. One Horse .300 BLK barrels are pistol gas at every length. One Horse 5.56 barrels are pistol gas at 7.5″, carbine gas at 10.5″ and on the 16″ M4, and mid-length on the 16″ SOCOM.

Gas and buffer go together

Short barrels, carbine gas and suppressors can run over-gassed, and a heavier buffer slows the carrier. Shopping a can? Start at the suppressors hub (Ashe 5.56 or Ryn .30 cal, Plan B mount included), or jump to Ashe vs Ryn and titanium suppressor weights. The H1 vs H2 vs H3 buffer weight chart gives a starting buffer for 10.5″, 14.5″, 16″, suppressed and .300 BLK builds.

FAQ

Common questions

What gas system do One Horse .300 BLK barrels use?

Pistol gas, on the 7.5", 10.5" and 16" .300 BLK barrels.

What gas system is the One Horse 10.5" 5.56 barrel?

Carbine gas.

Which One Horse barrel is mid-length gas?

The 16" 5.56 NATO SOCOM barrel, which is also 1:8 twist.

Which is longer, carbine or mid-length gas?

Mid-length. From shortest to longest the common lengths are pistol, carbine, mid-length and rifle.

Questions? Email customerservice@theonehorse.com.