The Difference Between AR-15 Buffer Tubes

The Purpose of the Buffer Tube

The buffer tube serves two very simple purposes. First it allows an individual to attach a stock to the weapon. The second thing is it houses the buffer and buffer spring that allows the rifle to operate effectively. That’s it!

Buffer Tube

The Different Types of Buffer Tubes

There are a few items you need to know before determining which buffer tube is right for you.

6061-T6 vs. 7075-T6: 7075-T6 has twice the tensile strength of 6061-T6. Most manufacturers will only use 6061 to decrease cost. You can see the difference in the strength in the chart below.

Alloy and Temper Form Tensile Strength
7075-T6 Forged 74
7075-T6 Billet 77
6061-T6 Forged 38
6061-T6 Billet 38
Note: Data taken from DOT/FAR/AR-MMPDS-01 Metallic Materials Properties Development & Standardization

 

Forged vs. Billet: This is an age-old argument that you will find numerous opinions on if you take the time to Google or look at forums. In reality, this is not an argument at all. If you look at the chart above you will see that there is little to no difference in strength. The only discernable difference is that because a billet alloy is completely machined it will have cleaner more concise cuts and lines. A forged alloy can also be machined, but the amount of material you can remove is limited, as it has been cast with a specific shape. This will make the lines and cuts not as clean and concise.

Rolled vs. Cut Threading

Rolled: Metal with rolled threads is created using a process that rearranges the metal into the required shape. This process does not remove any material.

Cut: Metal with cut threads requires machining or more specifically lathing that removes material until the required shape is created.

In a study done by Birmingham Fastener Manufacturing in 2000, they measured the tensile strength for both rolled and cut threads. In this study, they took four samples from each material in a controlled study and found that rolled threads are 7% stronger than cut threads.

You can view the results here.

Mil-Spec Buffer Standards

Material: Typically 7075-T6

Manufacture Process: Forged

Threading: Rolled

Pros: If you took the time to read about materials, manufacture process, and threading you will notice that the Mil-Spec Buffer tube has the best of all worlds. Plus there are more options for stocks available on the market for your rifle.

Cons: None

Commercial Buffer Standards

Material: Typically 6061-T6

Manufacture Process: Billet (i.e. Bar Stock)

Threading: Cut

Pros: This is a good cheap alternative to a Mil-Spec buffer tube.

Cons: There are no military standards and no quality control from company to company. Fewer options for stocks exist in the current market compared to Mil-Spec.

TheARGuys Opinion

In our opinion, you should always go with a mil-spec buffer tube. It allows you to choose from a variety of manufactures for the tube itself as well as stocks for your rifle. On top of it all the military holds companies to a strict standard if they want their parts to be used in the field. This forces companies to use better materials and manufacturing processes.

 

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5 Responses

  1. Michael Cherney says:

    Hello I like your articles
    I hope you could help me I am doing my first AR build I am doing a 80% and just ordered the Lower part kit an Anderson 7615 remington will this work well for me?

  2. Michael Cherney says:

    Yeah, now I’m waiting for my parts kit to arrive the hammer looks so different on the Anderson 7615 trigger kit but the lower is the same if I understand correctly a much better trigger for plinking

    • abraun says:

      You will be fine. Just make sure when you mill the lower that it is within the proper tolerances. The hammer and kit are standard and will work. The hammer is a bit bigger but nothing to be worried about. There are a number of different types of trigger and hammer configurations on the market. I am surprised you decided to go with a 80% on your first build. It adds an extra level of complexity, so good luck.

      • Michael Cherney says:

        Thank you
        Well when I grew up we had a mill in the garage didn’t then but now that I am older miss milling and just target shooting is to expensive so I figure I will start building and reloading and I will have something to show for it building a 300 Blackout never fire an ar
        I have handled and fired and been around a lot of firearms when I was young
        And I really would like to see and do
        3gun looks amazing.

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