Geissele Automatics Reliability Enhancement Kit H2

The Geissele Automatics Reliability Enhancement Kit H2 is a complete bolt carrier group and buffer system upgrade for 5.56mm AR-15 pattern rifles. If you run your carbine hard—whether for competition, tactical training, hunting, or duty—this kit addresses the weak points in a standard operating system with purpose-built components designed to feed reliably under demanding conditions. Geissele engineered the REK over years of field testing to deliver measurable improvements in reliability without requiring calibration or guesswork on your part.

At the heart of the kit is the Geissele Reliability Enhanced Bolt Carrier Group (REBCG), a full-mass, full-auto rated assembly that handles 5.56 NATO with authority. The carrier itself is machined from mil-spec 8620 steel and incorporates extended upper rails that visibly differ from standard designs—those rails stabilize the bolt and dramatically improve feeding consistency, particularly with marginal ammunition or magazines. The gas key is properly torqued and staked per military specification. The cam pin is machined from H13 medical-grade steel and receives Nanoweapon coating for corrosion and wear resistance. The bolt is where Geissele separated itself from the pack: it's forged from Carpenter 158+ material (a premium alloy developed collaboratively with Carpenter Steel) rather than the minimum specification the government requires. This translates to a bolt with five times the service life of a mil-spec unit. Every bolt passes magnetic particle inspection and high-pressure testing before coating.

The kit pairs the REBCG with Geissele's Super 42 Braided Wire Buffer Spring and H2 buffer. The H2 configuration suits standard-length carbine-gas systems and mid-length rifles running typical 5.56 loads. Nanoweapon coating throughout the system provides hardness equivalent to 82HRC, which means carbon wipes away easier and you'll run the gun cleaner with less lube. This is a complete, drop-in upgrade—no tweaking, no tuning, no guessing. If reliability matters and you're willing to invest in components proven to work, the REK H2 is the upgrade path.

Key Features

• Full-mass, full-auto rated M16/M4 pattern bolt carrier group for 5.56mm AR-15 rifles
• Extended upper rails on carrier for enhanced feeding reliability and bolt stability
• Geissele Stressproof Bolt forged from Carpenter 158+ steel—rated for five times the service life of mil-spec bolts
• H13 medical-grade steel cam pin coated in Nanoweapon for corrosion and wear resistance
• All components coated in Nanoweapon (Picatinny Arsenal-derived coating) for superior hardness, corrosion resistance, and low-friction operation
• Properly torqued and staked gas key per mil-spec
• Includes Super 42 Braided Wire Buffer Spring and H2 buffer for carbine-gas and mid-length systems
• Manufactured in Geissele's North Wales, PA facility
• Each bolt undergoes magnetic particle inspection and high-pressure testing

Specifications

Frequently Asked Questions

What's included in the Reliability Enhancement Kit H2?

The kit includes the complete Geissele Reliability Enhanced Bolt Carrier Group (REBCG) and the Super 42 Braided Wire Buffer Spring with H2 buffer. It's a complete system ready to install into your AR-15 upper and lower.

Which AR-15 gas systems does the H2 configuration work with?

The H2 buffer is designed for carbine-gas and mid-length AR-15 rifle systems running standard 5.56 NATO loads.

How does the Nanoweapon coating improve reliability and maintenance?

Nanoweapon is a low-temperature coating with hardness equivalent to 82HRC—the same family of coatings developed by Picatinny Arsenal. This hardness allows carbon and fouling to wipe away more easily, so you can keep the gun running cleaner and with less lubrication than standard coatings.

Is the bolt really stronger than a mil-spec bolt?

Yes. The Geissele Stressproof Bolt is forged from Carpenter 158+ steel (a premium alloy developed with Carpenter Steel's metallurgists) rather than the government minimum specification. The bolt is rated for five times the service life of a standard mil-spec bolt and undergoes magnetic particle inspection and high-pressure testing before coating.