The Geissele 5.56mm Reliability Enhanced Bolt Carrier Group 05-2993 is a full-mass, full-auto rated M16/M4 BCG built around one core idea: reliability starts with the bolt, not just the coating on top of it. Manufactured at Geissele's North Wales, PA facility, this Geissele BCG is engineered for the kind of round counts that expose weak points in lesser carrier groups. At the heart of this 5.56 Bolt carrier group is the Stressproof Bolt, forged from a specially developed Carpenter 158+ material, created by working directly with Carpenter Steel's own metallurgists to produce a cleaner alloy with fewer impurities. Forging the bolt, rather than machining it from bar stock, reshapes the grain structure of the metal itself, and the result is a bolt Geissele rates at five times the service life of a mil-spec bolt. Every bolt is high pressure tested, magnetic particle inspected, and individually checked before it ships. The carrier itself is machined from mil-spec 8620 steel with extended upper rails that improve stability in the receiver and noticeably reduce feeding issues. The gas key is chrome lined, properly torqued, and staked for long-term function, while the cam pin is machined from H13 tool steel, the same material used in medical instrumentation, then coated for durability. The entire Geissele Enhanced BCG is finished in Nanoweapon, a Chrome-Nitride coating that adds real resistance to corrosion, carbon buildup, and wear. For shooters who put real volume through a rifle and expect the internals to keep up, this Geissele Bolt Carrier group is built specifically for that demand. Key Features Full-mass, full-auto rated M16/M4 bolt carrier group Stressproof Bolt forged from specially developed Carpenter 158+ steel Rated for 5 times the service life of a mil-spec bolt Extended upper rails improve stability and feeding reliability Chrome-lined, torqued and staked gas key Cam pin machined from H13 tool steel Nanoweapon Chrome-Nitride coating for corrosion and wear resistance Manufactured in Geissele's North Wales, PA facility Geissele Automatics Geissele 5.56mm Reliability Enhanced Bolt Carrier Group 05-2993