AR Buffers - A Key Subsystem

Absorb, store, and release

The buffer system of an AR weapon is a critical subsystem. Understanding this subsystem helps in designing your build and understanding it can help in solving problems.

The subsystem has three parts. Those are the buffer tube, the buffer spring, and the buffer. I’ll cover the buffer retainer as a part of the lower receiver in a future article.

These three parts must be matched with the gas system, the bolt carrier group, and the caliber. Matched means that these three parts absorb, store, and release the right amount of energy when a round is fired. The right amount is enough energy to extract the fired cartridge, move to the rear far enough to pick up a fresh cartridge (or to lock back if the magazine is empty), to chamber the fresh cartridge, and to lock the bolt into battery.

The amount of powder burned, the powder burn rate when the weapon is fired, and the placement of the gas port on the barrel are key to the barrel design for a particular caliber.