Geissele Reliability Enhanced Bolt Carrier Group (BCG) for AR15 / M4 / M16


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Geissele BCG Overview

Geissele Reliability Enhanced Bolt (Geissele BCG) Carrier Group (BCG) for AR15 / M4 / M16


  • Full auto rated
  • M16 Profile
  • 8620 Carrier
  • C158 Bolt
  • H13 steel cam pin
  • Improved upper rails
  • Nanoweapon Chrome Nitride finish
  • HPT and MPI


The Reliability Enhanced Bolt Carrier Group (REBCG) is a 5.56mm full-mass, full-auto rated M16/M4 bolt carrier group.  The carrier machined from mil-spec 8620 steel, and features a properly torqued and staked, chrome lined, gas key. The cam pin machined from an advanced medical steel typically used to produce medical instrumentation known as H13, it then coated with Nanoweapon (Chrome-Nitride) for maximum corrosion and also wear resistance. The extended upper rails on the carrier also provide much greater stability and also dramatically increase feeding reliability. The Carrier coated with Nanoweapon for maximum corrosion and wear resistance.

Geissele Stressproof

The Geissele Stressproof Bolt forged and made from Carpenter 158 steel allow.  Geissele engineers worked the Carpenter Steel metallurgists to produce a new allow known as Carpenter 158+. This material is cleaner with less impurities, ultimately making it stronger and more consistent. Geissele believes the combination of forging and Carpenter 158+ allow steel makes the bolt capable of 5 times the life of a mil-spec bolt. Each bolt then rigorously inspected, high pressure tested, mag particle inspected and also coated with Nanoweapon for maximum corrosion and also wear resistance.

I gotta admit, Charlie was skeptical.


Nanoweapon a family of coatings similar to DSL (Durable Solid Lubricant) that developed by Picatinny Arsenal (US ARMY ARDEC), and available exclusively on Geissele parts. Geissele spent 3 years with the research and development company that worked with Picatinny to develop the coating to tune it into what it is today, which Geissele believes is one of the best coatings for firearm components.  The coating applied at low temperatures so it does not affect the metallurgy of the part, and also has a surface hardness equivalent of 82HRC. normally with less lubrication.


Geissele spared no effort in design, craftsmanship, machining and materials.  The first thing that sticks out that the extractor a lighter colored steel, and stands out from the rest of the Bolt.  The next thing you notice this not a standard phosphated steel, but also a slick coating.  You might tempted to think Nitriding, or QPQ, or DLC, or Ion bonding.


These all great coatings, but Geissele developed their own coating that applied in a very different fashion,  No hot acid baths.  No vacuum chambers with positive and negative ions floating in space.  The coating is in the family of durable solid liquids.




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