The buffer tube system, which consists of an aluminum tube that houses the buffer weights and spring, is perhaps the least-understood mechanism of AR-15 operation.
Yet the buffer weight you choose is critical to performance of the rifle, ensuring fluid cycling, optimal extractor, and quick action time.
Here’s what you need to know about it.
What the Buffer System Does
The buffer system, which consists of the tube, spring, and buffer weights, is central to the action of the rifle.
When you fire the rifle, some of the gas expanding from the deflagration of the propellant gets siphoned off into the gas system, where it travels back and exerts pressure on the bolt carrier group’s gas rings.
This pressure pushes the BCG back, extracting and ejecting the spent cartridge. It also puts the BCG in contact with the weights in the buffer tube, which offer resistance.
This resistance helps to absorb some of the recoil of the rifle; it also works against the buffer spring, which continues to slow the rearward progress of the BCG, and which stores potential energy to cycle the action and return the BCG to battery.
In short, the rifle action would not reset without the buffer system, but that’s just the tip of the iceberg. The buffer weights themselves also impact performance.
Tuning a Rifle: Why Buffer Weight Is Central
For most AR shooters, when you’re talking about tuning a rifle, what you’re talking about is adjusting the buffer weight.
This is because, though adjustable gas systems exist, for the most part, AR-style platforms have fixed gas systems. That means the main component of the action you can tinker with is the buffer system, specifically the weights.
Common Buffer Weights
For carbine-length rifles, the most common buffer weight is a carbine buffer weight, which weighs 3 ounces.
AR-15 pistols take a special buffer system (usually) known as a pistol buffer. You might think that a pistol buffer, since it is smaller and lighter, would take a smaller buffer weight, but this is actually not the case. This is because AR pistols tend to have heavier BCGs, and some have different gas systems. Pistol buffers weigh between 5 and 8.5 ounces, which helps to ensure smooth cycling and reliability.
That leaves us with buffer weights for rifle-length platforms. The most common of these is a standard H or “heavy” buffer, which weighs 3.8 ounces. This standard weight is suitable for most rifle-length platforms and generally produces good feeding and extraction with most common sporting rifle cartridges.
The next step up is an H2 buffer, which will weigh between 4.6 and 4.7 ounces. These buffer weights are common on rifles with mid-length gas systems and offer good performance for builds chambered in 5.56 NATO (or .223 Remington, of course).
Then we have H3 buffers, which again are a bit heavier, at 5 to 5.4 ounces. These H3 buffer weights offer better performance with larger cartridges that fire heavier bullets, such as 7.62x39mm (AKA 7.62 Soviet) or .300 Blackout. The heavier buffer weight not only helps absorb recoil, but it also helps reliably cycle the heavier rounds. A stiffer spring should be used with a heavier buffer weight, too.
Buffer Tube Weights by Barrel Length and Gas System
Another way to look at this is from the perspective of the rifle gas system and barrel length. If your rifle has a barrel 18” or greater, with a mid or rifle-length gas system (and is not suppressed), it should run just fine with an H1 buffer weight.
If your rifle is shorter, with a barrel between 14.5” and 16”, and is not suppressed, it should run fine with either an H1 or H2 buffer weight. If the rifle is suppressed, this will increase chamber pressures, so a heavier weight is preferable.
Any build with a barrel shorter than 11.5” inches (and paired with a carbine-length gas system) should be outfitted with an H2 or H3 buffer weight. If the rifle’s recoil is heavy, extraction is erratic, the rifle is suppressed, or paired with a heavier cartridge, err on the side of a heavier buffer weight. H3 may be the way to go.
Upgrade Your Rifle’s Buffer Tube Weights Today
Upgrading your rifle’s buffer tube weight can have considerable impacts in recoil reduction, improved extraction and cycling, and more. Yet it is a simple and somewhat overlooked upgrade that can be made very easily and at home - all you need to do is partially disassemble the rifle, remove the buffer tube and replace the weights.
If you’re interested in looking at different buffer tube and weight upgrades, take a look at what we carry here - we even carry buffer tubes for SBRs and short buffer tubes and AR-15 pistol builds. Check them out here and get in touch with us at Sales@MCSGearup.com if you have any questions.