Geissele Reliability Enhancement Kit (REK)



Product Description

The Geissele Reliability Enhancement Kit includes the Geissele Reliability Enhanced Bolt Carrier Group and the Geissele Super 42 Braided Wire Buffer Spring & Buffer in your choice of H1, H2, or H3 configuration for 5.56mm AR-15 pattern rifles. The Geissele REK is the culmination of many years of extensive testing and fine-tuning to bring you the most reliable operating system upgrade you can make to your carbine.

The Reliability Enhanced Bolt Carrier Group is a 5.56mm full-mass, full-auto rated M16/M4 bolt carrier group manufactured in Geissele’s state-of-the-art manufacturing facility in North Wales, PA. The carrier features a properly torqued and staked, Chrome Lined, Nano coated, gas key. The cam pin is machined from advanced tool steel also used to produce medical instrumentation known as H13, it is then coated with Nanoweapon (Chrome-Nitride) for maximum corrosion and wear resistance. The extended upper rails on the carrier also provide much greater stability and dramatically increase feeding reliability. The Carrier is coated with Nanoweapon for maximum corrosion and wear resistance.

The Geissele Stressproof Bolt is made from Carpenter 158, however, this is not your typical material spec’d by the US Government. Since Geissele wanted to take it to the next level, Geissele engineers worked directly with the Carpenter Steel metallurgists in Reading PA, to produce a special type of material known as Carpenter 158+. This material is cleaner with fewer impurities, ultimately making it stronger and more consistent. They did not stop there, they decided to forge the bolt. Using the same process used to produce upper and lower receivers, a forged bolt manipulates the grain structure of the metal and yields a bolt capable of 5 times the life of a mil-spec bolt. Each bolt is then rigorously inspected, high pressure tested, mag particle inspected, and coated with Nanoweapon for maximum corrosion and wear resistance.

Nanoweapon is a family of coatings similar to DSL (Durable Solid Lubricant) that was developed by Picatinny Arsenal (US ARMY ARDEC) and is only available exclusively from Geissele Automatics. Engineers worked for over 3 years with the research and development company that worked with Picatinny to develop the coating in order to fine-tune it into what it is today, making it the pinnacle of coatings for firearm components. No other coating on the market can provide the same level of corrosion, wear, and abrasion resistance as Nanoweapon. The coating is applied at low temperatures so it does not affect the metallurgy of the part and has a surface hardness equivalent to 82HRC. At that hardness, it is harder than sand, easily rejecting carbon and making cleaning a breeze, on top of allowing the firearm to operate normally with less lubrication.




Technical Information

Caliber 5.56 NATO / .223 Remington
Finish Nanoweapon
Material Carpenter 158+

Catalog Location

California Prop 65 Warning

WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information visit