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!

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 manufactures 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 assault 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 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 assault 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.