For those looking to match the specs and performance on the M4A1 SOCOM Block II carbines used by troops during Operations Iraqi Freedom and Enduring Freedom, the Daniel Defense M4A1 SOCOM Block II Upper Receiver is a great starting point.
The Daniel Defense M4A1 SOCOM Block II Upper Receiver features a quad-rail handguard equipped with a Picatinny-compatible rail sections. The barrel is constructed from mil-spec chrome-moly vanadium steel and features a standard Government profile (current SOCOM issue) with a chrome-lined interior, matching military-style barrels with the same construction.
The Daniel Defense M4A1 SOCOM Block II Upper Receiver features a flat dark earth anodized finish. The rifle can be had with an F-marked front sight gas block or a low-profile gas block under a full-length forend.
The Brownells M16 5.56 Complete Bolt Carrier Group is an affordable option that is built and tested to provide flawless operation in any AR-15 or M16.
The Brownells M16 5.56 Complete Bolt Carrier Group features a bolt fabricated from 9310 steel that includes a heat-treated and shot-peened finish. The bolt carrier itself is built using 8620 steel, which features a hardened finish. The whole BCG is completed with a nickel-boron coating.
The Brownells M16 5.56 Complete Bolt Carrier Group features a full assembly that includes the bolt, bolt carrier, gas key, firing pin, cam pin and a firing pin retaining pin.