Geissele 05-2993: 5.56mm Reliability Enhanced Bolt Carrier Group The Geissele 5.56mm Reliability Enhanced Bolt Carrier Group 05-2993 is engineered for maximum durability and performance in demanding conditions. This full-mass, full-auto rated M16/M4 BCG is precision-manufactured in Geissele's cutting-edge facility to exacting standards. Geissele 05-2993 features an extended upper rail design that enhances stability and significantly improves feeding reliability. The chrome-lined, nano-coated gas key is properly torqued and staked for long-term function. Finished with Geissele's advanced Nanoweapon coating, the entire carrier boasts exceptional resistance to corrosion, carbon buildup, and wear, making it ideal for high-round-count, hard-use applications. Geissele 5.56mm Reliability Enhanced Bolt Carrier Group 05-2993