12.5 inches, the perfect length for an AR barrel (VIDEO)
By Ben Brown
There are a variety of AR-15 barrel lengths and styles out there. Some short. Some long. But what would you say is just right? Considering things like reliability, speed, accuracy and maneuverability to find a length that works for multiple purposes, I would have to say 12.5 inches.
Can we talk about reliability
A 12.5-inch carbine gas length is a very reliable length. And reliability is the highest priority. This barrel configuration will provide ample dwell time – the amount of time the bullet spends in the barrel between the gas block and muzzle – for the round. This determines how much gas goes back into the BCG to make it cycle.
(Source: Small Arms Defense Journal)
When we shorten the barrel from 20 inches, the gas port has to move back as well. Then, when a barrel gets shorter than 10 inches, it will require a pistol length gas systems, which tend to have problems because of excess gas. Rifle, Mid-Length, and Carbine gas lengths are ideal lengths provided that you have enough barrel after the port to create enough dwell time. When the dwell time is minimal (gas port is close to the muzzle), AR rifles become unreliable.
Can we talk about speed