Once upon a time I was a Marine and the first rifle I was issued was an M16A2, followed by an M16A4. While the length of a gas tube will in part be dictated by the length of barrel used, it doesn’t have to be.Ī standard 16″ barrel normally comes in Carbine and Mid-Length gas systems but can sometimes use a rifle length gas system – although rifle length is normally found on barrels of 20″ or more. Gas Systems, being plural, refers to the gas block and the length of the gas tube. These three AR-15 components are the most important when it comes to tuning the rifle. The three parts of the gun you need to pay attention to is the gas system (which includes the gas block and gas tube), the bolt carrier group, and the buffer. The BCG then picks up the next round in the magazine and pushes it into the chamber. Once the spring hits its apex the buffer pushes the BCG forward. The BCG travels backward into a buffer, which compresses a spring. This gas is then shot back into the receiver and it forces the bolt carrier group rearward.Īs the BCG travel rearward it extracts and ejects the fired round. This gas port bleeds off some of the gas through a gas tube.

As the gunpowder ignites it creates gas which propels a projectile down the barrel.Īs the gas travels down the barrel it reaches a gas port which is part of a gas block. You aim, pull the trigger, and the gun fires. AR-15 firing cycleįirst, you manually load a round. I think a firm understanding of how the gun runs is a must have to understand the rest of the article fully. Let’s break it down on how the AR-15 functions really quick. Specifically, it’s a direct impingement gun. Speaking gas systems, if you didn’t know the AR-15 is a gas-powered gun.

Yay, education! Understanding the AR’s Gas System(s) You’ll learn a lot about your rifle, and how a gas system works. Finally, tuning your gun can both be fun, and interesting to do.

Buffer spring for subsonic 223