Mil-Spec VS Commercial Buffer Tubes

 AR-15  Adjustable Receiver Extensions (commonly known as ‘Buffer Tubes’)

When it comes to buffer tubes there are many manufactures and many, many choices such as  A2, PISTOL, CARBINE,  MIL SPEC,  COMMERCIAL, 6 POSITION, 4 POSITION, 5 POSITION ETC… which can lead to confusion. This is why we are only focusing on the most common style the Carbine.

The Carbine Multi-Position Buffer Tube comes in 2 styles, Mil-Spec or Commercial

• Mil Spec = 1.145” – 1.150 O.D
• Commercial = 1.165” – 1.170” O.D.

The sizing above refers to the outside diameter of the tube itself where the stock slides over. The Threads of the buffer tube are also different between the Mil Spec and Commercial as well as a few other items.

NEVER ATTEMP TO ATTACH A MIL-SPEC STOCK TO A COMMERCIAL TUBE

It is important to know which tube you have as this impacts your selection of a buttstock. A Mil-Spec stock will NOT fit on a commercial tube. However a commercial stock will fit a mil-spec tube but be woobly.

You will first notice the Commercial tube is slightly larger than a Mil-Spec tube, however without the use of a Micrometer or Caliper it is difficult to tell the difference between the two, luckily there is a visual indicator Most Commercial tubes will have a 5º deg slanted cut in the rear. A true Mil Spec Tube is only a 4 position tube and Commercial is a 6 position, however in recent years this has changed as there are many manufacture whom make a 6 position Mil Spec tube. So you cant always rely on the Position or the Slant cut to determine which tube you have.