The Difference Between AR-15 Buffers

carbine_buffers_2_Before we get into the differences of each available buffer I would like to review the most important piece of information you need to know before selecting a buffer.

Purpose of the Buffer

The buffer is one of many pieces that helps your rifle to operate normally. When a bullet has fired the energy that it released pushes the bolt carrier backwards which then connects with the buffer within the buffer spring and tube. At the point of contact, the buffer pushes the spring backwards. Depending on the weight of the buffer and the strength of the spring the buffer will reconnect with the bolt carrier pushing a new bullet forward into the chamber to be fired.

Why does the weight of the buffer and strength of the spring matter?

We will start with the buffer spring. Most springs are fairly standard, but you will encounter different variations on the market. Look for the one that best aligns to your rifle and you will be fine. As for choosing the proper buffer weight that can be a little tricky. If you get a weight that is too heavy the rifle won’t be able to push the spring back and reload the weapon. If you get a buffer that is too light then bolt carrier might move too fast and not perform the proper functions. To learn more about the buffer weights, keep reading…

Buffer Weights

Now it’s time to get the reason you are here. What are the differences between each buffer that is offered on the market today?

Well, have a look….

Carbine Buffer (Avg 3.0 oz)



Includes 3 Steel Weights

Heavy (H) Buffer (Avg 3.8 oz)



Includes 1 Tungsten + 2 Steel Weights

H2 Buffer (Avg 4.7 oz)



Includes 2 Tungsten + 1 Steel Weights

H3 Buffer (Avg 5.6 oz)



Includes 3 Tungsten weights

Rifle Buffer (Avg 5.0 oz)



Includes 5 Steel Weights + 1 Steel Spacer

*Note that these are approximate weights. Each manufacturer creates products that range between the mil-spec standards.

One of the great benefits of a properly matched buffer and spring is the ability for the combo to reduce recoil! Everyone loves less recoil! But don’t get too excited, it takes proper care and matching of the buffer and spring to make sure that you are not reducing the energy to a point where the bolt carrier won’t reload the weapon.

What are buffers made of and why?

Most buffers on the market today are made of aluminum, steel, tungsten and rubber. You will notice from the chart below that the primary materials are Steel and Tungsten. The reason for this is because both metals are extremely heavy and dense. In fact, Tungsten is heavier than both Uranium and Gold while costing significantly less. The only metals that weigh more are Platinum, Iridium, and Osmium.

Type Weight*
Aluminum  .098lb PCI
Steel  .283lb PCI
Lead  .409lb PCI
Tungsten  .700lb PCI





*Note: Weight is measured per cubic inch (PCI) and is dependent on density.

What buffer is right for me?

This is the question everyone is trying to answer isn’t it! Like I said before, when it comes to buffers it all depends on your setup. But when in doubt stick with a standard H buffer for collapsible stocks and rifle for a full size stock.


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18 Responses

  1. jtsmith says:

    I have put a bump stock on my AR . Do you think i might want to change the buffer weight and maybe the spring?

    • Aaron Brown says:

      It will work both ways. That being said, you are putting a large amount of wear on your current spring if you are using it regularly and I would advise moving to an H2 with Chrome spring.

      On another note, I am not a big fan of bump stocks. It is a cool idea and it works. If you are looking to have some fun and shoot at fast speeds then go ahead. In reality, it just decreases your accuracy and wastes ammo.

    • Ryan says:

      Putting a bumpfire stock on you AR is more of a novelty and not recommended by the AR guys for a service type rifle. You will go through a lot of ammo and it is safer to use a actual NFA registered machine gun, but that cost thousands more and you have to wait for permission from the ATF to do that. When it comes to the buffer and spring combo we would recommend a M16 bolt carrier and an H buffer to decrease the cyclic rate. This makes things more reliable and less likely to get bolt bounce. A Chrome Silicon Spring will give you longer service life since you will also be burning through more ammo faster.
      Let us know how it goes.

  2. scott says:

    I’m building an AR in 7.62×39 do I need a different Buffer and spring? What do you suggest?

    • Aaron Brown says:

      Hey Scott,

      Sorry for the late reply. They use the same spring and buffer. That being said, remember that 7.62’s (AR-10) platform are not the same across the industry. You can buy DMPS AR-10 parts and try to fit them with Rock River parts and they might not work. If you are building an AR-10 stick with the same manufacturer throughout the process or do a lot of research. Let me know if you have additional questions.


  3. Bob says:

    How can I tell if my buffer spring is SS or CS?
    I recently bought “AR-Stoner Receiver Extension Buffer Tube Assembly 6-Position Mil-Spec Diameter AR-15 Aluminum Black” from MidwayUSA, Product #: 866002, for $35 and am left assuming it is SS due to the price.
    Is there an easy way to tell the difference?

    • Aaron Brown says:

      Hey Bob,

      Yes, it is very easy to tell. Both the texture and rigidity is different. CS are not stiff and are almost flimsy feeling. SS will be very rigid. Most likely you have the SS for that price.


  4. Jason B. says:

    I’m looking to upgrade my spring and buffer, I currently have the cheaper/common set up and would like to upgrade it. There is a gun show this weekend and I was thinking of buying there. How can I know what I buy should work, seems like this is kind of a trial and error process?


    • abraun says:

      Hey Jason, Sorry for the late reply. Most of the stuff you find at gun shows, especially buffers and springs are garbage. I would purchase online if you can. On occasion, you will find a retailer carrying chrome silicone springs. Buffers will be easier to find, but I would buy new and most gun shows carry used. Let me know if you had any luck. -TheARGuy

  5. David says:

    I plan to build an AR-15 pistol. What kind of buffer do you recommend? Is there an option for a shorter tube with a different buffer/spring? I plan to use a CS spring (as you recommend) if possible.


  6. Scott says:

    I have a twenty inch barrel. I bought a six position carbine buffer tube for a bump fire. I know this is bad now. Can’t find a riffle buffer tube for bump. Tried to purchase 5oz damage industries conversion. Out of stock. I have a m16 bolt carrier and a 3.5 Single stage triggger. Can u recommend something?
    I just want it to work, it’s getting personal! Lol

  7. Danny says:

    Hi Im having some ejection problems seem like i tried different kinds of ammo, grain but still ejects at 2:00 position even added a h2 buffer but still made no different guys right next to me shooting is distracted by the case flying on his sights im running a 16 inch piston upper with a carbine buffer spring with carbine collapsible stock

    • abraun says:


      Glad you reached out. There are two ways to go about “fixing” your issue. The reason I say “fixing” is because its not technically an issue. Every rifle build throws differently. If you want to change the throw position you have to change the tension on the ejector spring. The easiest way to do this is to buy a new extractor spring online and replace it or just replace the bolt altogether. They typically come in kits with extractor and ejector spring. If you want another quick and dirty solution, just buy a brass deflector. They attach to the side of your rifle and its a plate the brass hits and then it drops to the ground. Does that help?


  8. Steve says:

    I just built a 24in AR using a CBC upper, Luth AR stock, A2 buffer and M-16 MIL Spc BCG and I have a cycling problem. It ejects spent brass just fine but won’t chamber the next round until the guns warms up, usually 4-5 rounds. Changed bolts (AR-15), put on a Carbine lower and different ammo did not help. Even after it warms up the bolt will not catch after last round. I was wondering about using a 3oz Carbine buffer in an A2 tube or getting a Low mass bolt or buffer?

    • abraun says:

      Hey Steve, It sounds like you have one of two issues. First issue, it could be crappy magazines. I would either try a quality Magpul mag or don’t fully pack your mag and see if it feeds properly. Second issue, your barrel doesn’t have feed ramps. This is a more common issue. The bolt is trying to cycle and push the round through but the front of the round gets caught on your barrel and doesn’t load properly. If you bolt is cycling all the way through and no jamming is probably your mags but I would take a look at both. Let me know what you find out.

      • Steve says:

        I used Magpul 30rd, 20 and 30rd Colt, D&H tactical and a couple of other make mags. None were loaded with more than 10rds The first round chambers when you release the bolt. Brass ejects and the bolt comes forward without the next round. After a dry fire, pull the charging handle, the next round chambers fine. After 4-5 rounds the bolt will catch a round but not chamber. Clear the miss feed and the rest of the mag works fine. If I do a quick mag change the next mag runs fine. If it sets for 15-20 minutes, the whole thing starts over.

        If I ride the charging handle, it chambers just like my 16 and 20in 5.56’s and 16in 300 ACC. If I hand charge or release the bolt, it never fails to feed. Those mag even worked on my 6.8 Rem Spc as long as I only loaded less than 5 rounds.

        I made a mistake the other bolt I tried was another M-16 and not my lighter AR-15.

        The CBC upper does not have an adjustable gas block but has a rifle length gas system. I’ll try the lighter bolt but I was wondering about a lighter buffer. J P Enterprises makes a 3oz for A2 length tubes but can I use the shorter 3oz carbine buffer?


  9. Steve says:

    Just got back from the range. It cycled every time with the lighter AR-15 bolt carrier but would not catch and stay open with an empty mag. I replaced the standard 5.1oz A2 buffer with a standard 3oz carbine buffer and it was perfect.

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