The buffer is a key component in an AR-15 rifle. However, even many people don't fully understand its role. It was discovered that by adding weight to the buffers, the recoil could be reduced. However, adjusting the weight can affect the overall balance of the rifle system, potentially causing issues.
When it comes to buffers, one size definitely doesn't fit all. Each rifle may require a specific type of buffer, depending on various factors. So, before you decide to swap buffers based on an internet post, pause and consider the potential implications. Incorrectly matched buffers can lead to serious issues that could compromise the reliability and safety of your rifle.
For example, adding additional weight to a buffer can cause the rifle to short stroke or not have enough port pressure to reload, particularly in cold weather. This is because ammunition functions differently in hot and cold weather, with cold weather creating a much lower port pressure. This underlines the importance of using milspec type buffers in rifles used for military purposes.
Quick Buffer Weight Selection Guideline
Assume no changes in bolt carrier group weight, recoil spring and ammo.
Over gassed - Increase the buffer weight
Under gassed - Decrease the buffer weight
Shell ejection forward of 3 o'clock position - Increase the buffer weight
The History of Rifle Buffers
The first rifle buffers were known as the Edgewater spring guides. These were the original buffers that came with the original Colt AR15 Model 01 rifles. These rifles were designed to run a hammer propeller, which gave a rate of fire around 600-700 rounds per minute. However, with the introduction of a ball powder into the mix, the rate of fire increased to nearly 1000 rounds per minute. This increased speed led to a phenomenon known as bolt carrier bounce, causing major failures during fully automatic fire.
The Impact of Bolt Carrier Bounce
Bolt carrier bounce is when the bolt carrier group closes during firing, causing the bolt to close, lock, and due to the impact, bounce back slightly, moving just out of battery. This causes the hammer to strike prematurely, leading to a misfire.
To rectify this, the standard buffer was introduced in 1968, which contained five steel weights separated by rubber discs. This buffer absorbed the shock from the bolt carrier and prevented it from bouncing backward and unlocking, ensuring reliable function even at higher rates of fire.
The Evolution of Rifle Buffers
Despite the success of the standard buffer, in the late 90s, Colt introduced a cost-cutting measure. They developed a buffer that provided enough weight to keep the bolt closed long enough, but removed the steel weights.
This buffer, however, failed to function in fully automatic rifles, leading to light strikes and malfunctions. This buffer was quickly replaced with the original standard buffer.
The Hydraulic Buffer
The next evolution in buffers was the hydraulic buffer. However, many hydraulic buffers failed to function correctly, primarily due to seal failure. One exception to this was the hydraulic buffer developed for the Colt Light Machine Gun (LMG).
This buffer helped reduce the rate of fire to around 700 rounds per minute, improving accuracy significantly. However, like all hydraulic buffers, there were issues with seal failure, requiring the creation of a rebuild kit.
The development of the carbine buffers brought more complexity. The original buffer used in the XM177 and XM177E2s was a shorter buffer with three steel weights. However, with the advent of the M4 carbine, a new buffer, the H2 buffer, was introduced.
This buffer contained one tungsten weight and two steel weights. The addition of the tungsten weight slowed the bolt carrier movement just enough to ensure proper presentation of the M855 round into the chamber.
The H2 buffer is characterized by its specific weighting: two tungsten weights and one steel weight. The buffer was developed during the M4A1 program for the SOCOM (Special Operations Command), which required a rifle with a heavier barrel.
The H2 buffer was conceived to rectify a specific issue. As the buffer moved rearward and the bolt closed, there was insufficient weight to halt the bolt carrier bounce. This issue became particularly pronounced when trying to fire a heavy barrel (such as the 14 1/2 inch heavy barrel) on fully automatic, resulting in light strikes. The addition of an extra tungsten weight provided the necessary heft to stop the bolt carrier bounce, ensuring a smooth and efficient operation.
While the H2 buffer is suitable for many applications, in certain circumstances an even heavier buffer is required. The H3 buffer, designed specifically for the Colt Infantry Automatic Rifle (IAR), contains three tungsten weights, making it the heaviest buffer Colt has ever offered.
The H3 buffer was created to tackle issues with light strikes resulting from the IAR's significantly heavier barrel. It's important to note that different buffers are designed for specific weapon conditions, enabling reliable function in various environments, whether it's the Arctic, desert, or temperate zones.
Impact of Barrel Weight
One key aspect to consider when dealing with buffers is the weight of the barrel. The heavier the barrel, the more bounce you get from the bolt carrier when it hits the barrel extension. This means that when you change not just the length, but also the weight of your barrel, you need to consider how it will affect the balance and operation of your firearm.
The heavier the barrel, the more weight you will need to provide to counteract the bolt carrier bounce. This is especially important when firing fully automatic. If you are using a standard buffer for semi-automatic firing, it won't make much difference, but for fully automatic firing, the H2 buffer becomes essential.