Posted by Nimrod’s Wares on Mar 16th 2016
One of the most common questions we are asked is whether a rifle requires a mil-spec or commercial aftermarket buttstock. Failing to order the correct one can result in a stock that is either too small to fit over the receiver extension (buffer tube) or has excessive play. So which buttstock type is needed? The answer depends entirely on the receive extension that was used by the manufacturer of the rifle in question.
Thankfully, there are a few simple ways to tell the difference. Several distinct features of the receiver extension determine whether yours is commercial or mil-spec. The easiest way to identify the type you have is to take a pair of calipers and measure the outside diameter of the tube. Mil-spec tubes are 1.148" in diameter while commercial are 1.168”. Don't have calipers? Remove your existing stock and look at the end of the tube (the end over which the buttstock fits). Mil-spec tubes have a flat closed end while commercial tubes are slanted at roughly a 5 degree slope. The third way you can tell is by the other end of the buffer tube: the threads. The outside diameter of mil-spec threads is noticeably larger than the outside diameter of the tube itself and each thread has a well defined peak. Commercial tubes actually have the threads cut into the tube, and peaks of each thread on a commercial tube are also slightly truncated or flat. If you are still unsure, please visit the Google search for Mil spec or commercial buffer tube, which includes hundreds of images which clearly show the difference between the two receiver extension types (one such image may be found here).
Regardless of the type with which your rifle came from the factory, you should not have any problem finding a stock to suit your needs from Nimrod's Wares (NimrodsWares.com). Most major manufacturers offer their best selling stocks in both mil- and commercial-spec variants, and Nimrod's Wares offers the full line of Magpul stocks in either spec, along with stocks from Fab Defense and Troy. If you don't see the exact stock you prefer, please do not hesitate to contact us – we will do our best to source it for you.
“…Nimrod the mighty hunter before the Lord” Genesis 10:9
All prices are in USD.