Frequently Asked Questions: Faxon Barrels & Compatibility with AR-15 Mil-Spec Uppers

We're thrilled to see Faxon barrels populating across the market and industry. In fact, all the photos our customers send in are sent throughout the office. As gun guys, we like looking at, talking about, and working on guns. Further, we're honored to see the selection of Faxon barrels in custom builds featuring parts from the best of the industry. 

Almost all AR-15 and component manufacturers (including Faxon) follow the same "Mil-Spec" created by the US Government for the M-16 rifle. As such, there are few, if any compatibility issues of components between companies. However, Faxon does receive inquiries on compatibility, which we are happy to field and answer. 

In short, Faxon barrels will be compatible with any AR-15 upper receiver, forged or billet, that follows the "Mil-Spec" tolerances. 

Specifically, Faxon barrel extensions are manufactured to exacting tolerances. All barrel extensions are precision ground (not just machined), post heat-treating to .9987" - .0006", which follows the military specification exactly. Further, Faxon uses custom ground hard gauging to individually check every single extension prior to mounting to a barrel. 

We don't know of many companies who follow this rigorous process, but for us, its standard practice. 

Faxon stands behind its products without hesitation. If you have any issue, with any upper receiver, please contact us and know our team will be with you until your weapon is performing to our high standards.