Faxon Firearms 14.5in Govt / Socom 5.56 NATO Mid-Length 4150 QPQ 15A58M14NSQ. 56 NATO Rifle Barrels Govt/Socom. Faxon Firearms crafts each of these AR15 Barrels from 4150 Mil-Spec steel or 416-R stainless steel and adds a Nitride finish inside and out...