AR-15 Stock Options: Mil-spec vs Commercial Buffer Tubes

Most AR-15 owners know what the buffer spring is and what it does - it helps absorb the kick created by a round firing and forcing the bolt carrier group back and loading another round. Whether you are in combat, hunting, or target shooting you will want to be familiar with the type of buffer tube on your AR-15. This can prove especially helpful if you are looking for a new stock as it will be necessary to match it to the corresponding buffer tube. While they are similar in function, there are some differences between the mil-spec and commercial buffer tubes that you should understand in order to make an informed decision.

Reason For Variation

There is a simple reason for the variation of buffer tubes. The mil-spec variation is more expensive to manufacture, so the commercial buffer tube is available for those who want a cheaper alternative. While similar in appearance, there are a few subtle differences that dictate the type of stock necessary for your weapon.

Mil-Spec Manufacturing Process

The mil-spec is unique in that the threads located at the front are larger than the diameter of the actual tube. To make the product, the threads are lathed with the use of a large tube. When complete, the rest of the tube is reduced down to the appropriate diameter. Due to this intricacy, it takes longer and costs more to purchase mil-spec buffer tubes.

Commercial Manufacturing Process

The commercial manufacturing process is more direct in that it begins by using a tube that matches the diameter of the final tube. Just as any thread, the commercial tube is then lathed into the front end. This process takes far less time than the mil-spec alternative, making the final product far less expensive.

Summing Up The Differences

When observing the commercial tube and mil-spec tube side by side, the differences can be hard to pinpoint, and that is because they may be slight and difficult to observe. However, just a small variation in diameter makes for an entire different experience when it comes to firing the weapon. The primary physical differences between the two types of buffers are:

• Product diameter
• Thread diameter to tube diameter ratio

It used to be that the main cosmetic differences were the number of adjustment holes for the stock as well as commercial tubes being slightly slanted at the end. The end of a mil-spec buffer tube is flat and many manufacturers of commercial tubes have gone in that direction to make them look similar. While you can buy a new buffer assembly if you want to switch from one to the other, it can be expensive when you combine that with a new stock.