A5 Buffer tubes are slightly longer (7.75″) than carbine buffer tubes (7.25″).
This extra length is really helpful for 308 cycling and reliability. It does slow down the rate of fire slightly, but can also help reduce felt recoil, improve feeding and reliability overall.
Our exact buffer setup is:
A5 Buffer Tube + 308 Heavy Recoil Spring + H2 Carbine Buffer
This setup has produced a very reliable AR 308 platform that shoots, feeds, and locks back on the last shot as intended. Our 20″ AR upper has a rifle length gas system, but we have also used this setup on carbine length gas systems.
It is generally recommended to have an adjustable gas block on your 308 build as they require some tuning before they are ready for the field!
Important: If you want to use this for a 556 build, then you need to use BCM’s proprietary buffer and buffer spring. We use this tube for 308 builds using a standard carbine length H2 buffer + 308 buffer spring. Using any other configuration could cause damage to internal components or render the gun less reliable.
