The Geissele Reliability Enhanced Bolt Carrier Group (REBCG) is engineered to deliver unmatched durability, smoother cycling, and extreme corrosion resistance for your 5.56mm AR-15. Built as a full-mass, full-auto rated M16/M4 BCG, this assembly is designed for shooters who demand absolute reliability in duty, defensive, and hard-use rifles.

The carrier features a properly torqued and staked, chrome-lined, Nano-coated gas key to ensure a secure gas seal and long-term dependability. Its extended upper rails enhance stability within the upper receiver, dramatically improving feeding reliability under adverse conditions. The carrier itself receives Geissele’s exclusive Nanoweapon coating, offering superior protection against wear, abrasion, and carbon buildup—keeping the BCG running cleaner, longer, and smoother.

At the heart of this system is the Geissele Stressproof Bolt, crafted from Carpenter 158+—a cleaner, stronger, and more consistent variant of the standard C158 alloy, developed in partnership with Carpenter Steel metallurgists. Unlike traditional bolts, this bolt is forged rather than machined, refining the metal’s grain structure for significantly greater strength and longevity—tested to deliver up to 5× the life of a standard mil-spec bolt. Each bolt is HP tested, MPI inspected, and finished with the same Nanoweapon coating for unparalleled corrosion and wear resistance.

Nanoweapon, developed exclusively for Geissele through years of collaboration with the R&D team behind the military’s DSL coating, offers an ultra-hard 82 HRC surface finish that rejects carbon, resists abrasion, and performs flawlessly without affecting metallurgy. The result is a BCG that stays slick, is easier to clean, and continues functioning in the harshest conditions—even with minimal lubrication.

Perfect for military, law enforcement, competitive shooters, and builders who refuse to compromise, the Geissele REBCG sets a new standard for premium AR-15 bolt carrier groups.