Forward Controls Design N M4 M16 Bolt Carrier Group Black Serrated FA Surface SBCG-N Serrated. It is Forward Controls Design view that the factory M16 carriers are very good and improvements over them would be hard to come by. Modern coatings have made them easy to clean and quite slick which we can appreciate. NP3 coating is rather expensive and time consuming which limits NP3 SBCG's production to about 200 units a year. SBCG-P is identical to the NP3 SBCG save for the coating of the bolt carrier and SCP/ICP (dimpled indexed cam pin) The S in SBCG stands for Secure Staking Slick Side. SBCG carrier has a series of serrations or dimples to aid in closing an out of battery bolt on upper receivers without a forward assist. The carrier still has forward assist pawl notches and so is compatible with forward assist equipped uppers. The Secure Staking aspect involves SBCG's use of Ned Christiansen's OCKS (Optimized Carrier Key Screws) which when staked properly offer significant improvement over conventional screws. OCKS have sharp deep and effective knurling that extends to the top of the screw head. These splines form pockets for carrier key metal to flow into when the key is staked resulting in gear tooth like engagement. Some argue that as long as the gas key screws are torqued to spec and staked properly OCKS aren't necessary. While I can't argue with that for us it is a matter of over building in areas where providing another layer of fail safe and redundancy is worth the negligible cost. Given the numbers below the choice of OCKS is an easy one to make. Install torque spec is 50-58 in-lb removal torque spec is 55-100 in-lb. Testing consistently found removal torque of YFS screws averaging around 76 in-lb with the OCKS consistently at 132 in-lb. Since Forward Controls Design 's so keen on the gas key's staking to ensure its immobility the question of one piece carrier had come up. It is our opinion that something different isn't always something better. Gas keys can crack and be dropped and damaged debris or primer can find its way into the gas key. Our view is based on reality not a theory as all of these have happened. A conventional carrier with a separate gas key can simply have its gas key replaced which is impossible for any one piece carrier. Each SBCG has its firing pin protrusion checked gas key torqued and staked and is individually test fired. SBCG will ship as is having been slightly lubed and dirtied by the test firing procedure. Surface is machined in the concave area (forward of the gas vents of the carrier) to facilitate silent bolt closing on upper receivers without a forward assist. SBCG carriers have a subdued and small Cygnus laser engraved. If you're looking for in your face billboard sized company logo Forward Controls Design's is not it. SBCGs are distinctive looking in their own right the subdued logo fits our philosophy and practice of modest to secret logo placement. It's an identifier not an advertising device. SBCG carriers are ASSI 8620 steel and machined to USGI specifications. The M16/M4 carrier includes a mil-spec gas key. The gas key is heat treated per TDP specifications and NP3 coated. The gas key is secured to the carrier via OCKS (Optimized Carrier Key Screws) torqued to spec values and properly staked. Specifications for Forward Controls Design N M4 M16 Bolt Carrier Group: Manufacturer: Forward Controls Design Color: Black Fabric/Material: 8620 Steel Gun Make: AR Platform Gun Model: M16 M4 Features of Forward Controls Design N M4 M16 Bolt Carrier Group SBCG bolts are manufactured from properly and correctly heat treated AISI 9310 steel. Each Bolt is MPI tested and inspected. Each bolt is shot peened and comes with a Sprinco heavy extractor spring and black O ring. The bolt and cam pin have been NP3 treated to enhance corrosion resistance and carbon build up. Bolt is stress relieved. Sprinco 5-Coil Heavy Duty Extractor Spring. Package Contents: Forward Controls Design N M4 M16 Bolt Carrier Group What firearm models does the manufacturer say Forward Controls Design N M4 M16 Bolt Carrier Group is compatible with? The manufacturer says that Forward Controls Design N M4 M16 Bolt Carrier Group is compatible with M4 M16Forward Controls Design SBCG-N Serrated: N M4 M16 Bolt Carrier Group Black Serrated FA Surface