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How to Choose the Right Buffer Weight for Your AR-15

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One of the most frequently overlooked components of the AR-15 is its buffer weight, a critical element in the AR-15’s buffer assembly. 

Despite its importance, enthusiasts often overlook changing or upgrading their buffer when optimizing their rifle setups. Changing your buffer to a different weight can change the entire feel of your rifle when shooting. It can lower the felt recoil, improve reliability, and even improve your split times.   

Today, we will explore the various buffer weights available for the AR-15, when to use them, and the benefits they can bring to your rifle:  

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Understanding AR-15 Buffers 

The AR-15 buffer assembly is comprised of three main parts: the buffer, buffer/recoil spring, and buffer tube. Both the spring and buffer are housed inside of the buffer tube, which is attached to the rear portion of the lower receiver. This assembly plays a key part in the cycling of the AR-15.  

After a cartridge has been fired, the gas system propels the bolt carrier group (BCG) rearward, where the BCG strikes the buffer. The buffer and spring catch the BCG, allowing it to cycle back and return to battery, repeating the cycle with each shot. Because of how crucial this assembly is when it comes to your rifle functioning, it’s important to make sure you have the right buffer weight.  

If your rifle is having problems cycling, whether it be a failure to eject, failure to feed, or failure to cycle, the buffer assembly could likely be the issue. If your buffer is too light or too heavy, it could lead to a multitude of problems, as well as increasing the amount of wear and tear on the internal components of your rifle.  

You can really fine-tune the cycling rate, felt recoil, and ejection pattern by simply changing out the buffer weight in your AR-15. While it seems simple, it can get complicated fairly quickly, as there are many weights to choose from.  

BCM Buffer Kit 01

Factors to Consider when Choosing Buffer Weight 

Adjusting your buffer weight can get you some great results, but at the same time, it can also be detrimental to your shooting experience if you choose the wrong weight. Before you put another buffer into your rifle, it’s important to know what different buffer weights can do to your rifle’s cycling, and when to opt for a certain weight.  

One of the main factors that determines what buffer weight you’ll need is whether your rifle is overgassed or undergassed. It’s fairly common for AR-15s to be slightly overgassed. This isn’t necessarily a problem, since higher gas pressures can help the rifle operate when it gets dirty or when in rough conditions. That said, overgassing can lead to problems like increased recoil, higher amounts of carbon build up, and lower shot velocities. 

Undergassed rifles have their share of issues as well. Lower gas pressures can hinder the rifle’s ability to properly eject rounds or cause feeding issues or other cycling issues. Generally, in these situations, it’s better to be slightly overgassed than undergassed. Regardless, they can both be mitigated by using an adjustable gas block and a new buffer weight.  

Whether you’re a seasoned AR-15 aficionado or a newer enthusiast, it’s a known fact that lighter recoiling rifles tend to be more fun to shoot and much more controllable when making quick shots in succession. Increasing your buffer weight can aid in reducing the amount of felt recoil your rifle has. A heavier buffer is more resistant to the forces put on from it the BCG after firing the rifle. More resistance means the BCG won’t recoil as hard into the buffer and spring assembly, effectively reducing the felt recoil.  

Switching to a heavier weight isn’t always the best option though. Keep in mind that since your buffer will resist the movement of the BCG more, the cyclic rate of your rifle will take longer. If you know that you’re going to be making quick shots in rapid succession, like in a competition setting, a too slow or too quick cyclic rate can make your rifle unreliable. Ideally, you’ll want to find the right balance between your gas setting and the buffer weight.  

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Common Types of AR-15 Buffers 

There are a lot of buffers to choose from, with some being better for other applications. It can be confusing to those who don’t know the differences between the buffers available. Fortunately, it’s much simpler than it appears, and below, we have a breakdown of each of the most common buffer weights:  

Carbine Buffer – 3-Ounce 

Carbine buffer weights are the standard weight that’s included in most AR-15s. This weight works best in mid-length gas systems but is commonly used in carbine gas-length ARs as well; just keep in mind that using this buffer with a carbine gas system will increase your felt recoil.  

This buffer weight is incredibly popular. It works with a wide array of calibers and ammo types including sub-sonic and high velocity ammunition.  

H1 Buffer – 3.8-Ounce 

There are a lot of buffers to choose from and the H1 is the lightest of them. This buffer weight is great for many kinds of rifle setups. Using this buffer can reduce the amount of felt recoil your rifle has, but it can also keep the bolt from unlocking too soon after firing a round. Under perfect conditions, the H1 buffer works better in a mid-length or rifle-length gas system. Each of the H buffers have the same length as the standard Carbine buffer and will fit in your rifle without modification. 

H2 Buffer – 4.6-Ounce 

This buffer weight has nearly an additional ounce of weight when compared to the H1. H2 buffers work exceptionally efficiently in carbine-length and mid-length gas systems, aiding with the rifle’s cycling ability while reducing felt recoil. Just about every rifle with a barrel between 13.7 and 16 inches can effectively run an H2 buffer when paired with the right spring. It’s also a great choice to use in AR-15 pistols and SBRs (Short Barreled Rifles).  

H3 Buffer – 5- to 5.4-Ounce 

The H3 is one of the heaviest of the H buffers, adding nearly 3 ounces to the standard Carbine buffer. H3 buffers are most commonly used in overgassed 5.56NATO AR-15s, as well as rifles chambered in other calibers. Generally, if the cartridge has a higher amount of muzzle energy, the H3 buffer is a great option to use.  

For instance, 300 Blackout and 7.62×39 have considerably more powder and muzzle energy when compared to standard 5.56NATO cartridges. Though the extra weight of the H3 buffer can still be used to great effect in a 5.56NATO rifle, it works best when paired with larger calibers like 300 Blackout, 7.62×39, and 6.5 Grendel. When used with these calibers, it has a better chance of increasing cycling efficiency while reducing felt recoil.  

Pistol Buffer – 5- to 8.5-Ounce 

Pistol buffers are used primarily on pistol caliber carbines (PCCs). Pistol caliber AR-15s don’t use or need gas systems to cycle the action. Instead, they use a direct blowback system. It’s one of the most basic firearm operating systems and works exceptionally well on pistol calibers since they don’t require any lockup to properly chamber the cartridge. That said, direct blowback PCCs often have higher felt recoil than their intermediate caliber counterparts and a pistol buffer provides enough weight to dampen the recoil felt by PCCs.  

Rifle Buffer – 5-Ounce 

A rifle buffer is almost double the length of the standard carbine buffer and is exclusively used in rifles with rifle length buffer tubes. One such example is the A2 buffer tube. It’s longer than carbine buffer tubes, and as such, it requires a longer spring and buffer. If you’re running an A2 stock and buffer tube on your rifle, you CAN NOT use any of the of the aforementioned buffers without switching to a carbine buffer tube first. Doing so will cause your BCG to slam into the back of the buffer tube with greater force, potentially damaging your rifle.  

If you’re wanting to change out your A2 stock to a carbine one, our guide on how to remove an A2 stock will walk you through the process. Below are some weight recommendations for AR-15s chambered in 5.56NATO:

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A5 Buffer System 

The A5 Buffer system from VLTOR, is certainly unique and incredibly versatile. It was initially designed and developed at the request of U.S. Marine Corps and was designed to mimic the smooth impulse of a rifle-length buffer assembly. As a result, it cannot be used with the standard carbine buffer tube.  

The A5 Buffer is slightly longer than the carbine buffer size, and as such, it requires a longer buffer tube and recoil spring, like an A2 length rifle spring, to use. Fortunately, A5 Buffer Tubes are relatively common, so you won’t have any difficulty finding an A5 system to match your setup. You can find A5 buffers similar to the weights mentioned above, and, depending on the manufacturer, you can find specialty weights like 6.08-Ounce and 6.83-Ounce too.  

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Changing out your Buffer  

It’s incredibly simple to change out your buffer with a new one. It does require some prep work though. Just like with any rifle modification, always make sure that your rifle is unloaded. Drop the magazine from the rifle, pull the charging handle back and lock it by pressing down on the bottom of the bolt catch. After ensuring that your rifle isn’t loaded, both visually AND physically, you can close the bolt and remove the upper receiver from the lower receiver.  

Once the upper is removed from the lower, depress the buffer detent to release the buffer and buffer spring from the buffer tube. Now that the buffer and spring assembly is out of the buffer tube, you can pull the buffer out of the spring. It will take a slight amount of force to remove the buffer, but it shouldn’t be too difficult.  

With your old buffer pulled from the spring, you’re good to put your new buffer in its place. Install your buffer into the recoil spring by pressing it into the spring until it’s fully seated. With your new buffer installed into the recoil spring, you can reinstall it into the buffer tube. Once installed, reattach your upper receiver to your lower and perform a function check to make sure that everything is working properly. If they are, you’re good to head to the range and try out your new buffer system.  

Though not necessary, it’s a good idea to clean your rifle while it’s disassembled. Cleaning off any carbon that has built up in the barrel, upper receiver, and on the BCG is much easier done when the rifle is disassembled. After cleaning, apply some oil or lubricant to your BCG to keep the action running smooth.  

If you plan on making more changes than just your buffer, it’s important to know how to disassemble and reassemble one if you plan on making upgrades to it. Follow our guide on assembling a lower receiver to see how it’s done, step-by-step.

BCM Milspec Carbine Stock Hardware Kit 01

Buffer Tube Kits and Specialty Buffers 

If you’re building a new AR-15 or simply interested in swapping out your current buffer assembly with an upgraded one, there are a multitude of buffer tube kits available. These kits come with all of the parts necessary to build out a buffer assembly on your lower receiver, including the buffer tube, recoil spring, and buffer itself, depending on the kit.  

While most kits come with standard/mil-spec parts, others from specific manufacturers come with upgraded components and specialized buffer weights. A few examples would be Bravo Company Manufacturing’s MK2 Recoil Mitigation System and Geissele Automatics’ buffer assembly with their Super 42 braided recoil spring.  

The Recoil Mitigation System kit from Bravo Company Manufacturing comes with an A5 buffer tube, their upgraded recoil spring, end plate, castle nut, and the buffer weight of your choice. The Geissele kit also comes with some mil-spec components, but included in the kit is their Super 42 braided recoil spring. This spring has a longer lifespan than the mil-spec recoil spring, and the braided spring works to remove any excess vibrations that can occur with standard ones.  

Depending on what you want to use your AR-15 for, these kits and specialized components might be worth considering adding to your build. There are some options available that are designed for use with suppressors, while others are specialized for SBRs and pistol builds. If you’re building a specialized AR-15 or are upgrading yours to be as such, specialized components can greatly enhance your shooting experience.  

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Buffer assemblies are often overlooked when enthusiasts start making upgrades to their rifles. However, when they’re optimized for a specific rifle, they make a world of difference, enhancing the shooting experience with less felt recoil and increased cyclic reliability.  

We highly encourage you to take full ownership of your rifles by customizing them to fit your needs and changing out your buffer assembly is just the start when it comes to customizing your rifle.  

So now that you know what to do about your buffer, check out our guides on the quick and easy upgrades to your AR-15 and the best pistol grips to see what else is possible.