Geissele Reliability Enhancement Kit REK H2 Buffer & REBCG 5.56 - 05-492-H2

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Geissele Automatics Reliability Enhancement Kit Parts Kit Includes Reliability Enhanced Bolt Carrier Group Super 42 Braided Wire Buffer Spring H2 Buffer Weight Silver 05 492 H2 UPC 817953026724

Product Description

The Geissele Automatics Reliability Enhancement Kit (REK) with H2 Buffer Weight (MPN: 05-492-H2) is a comprehensive operational drive-system upgrade designed to maximize mechanical reliability, bolt lockup integrity, and recoil management in 5.56 NATO / .223 Rem AR-15 carbines. Engineered specifically for hard-use duty carbines, suppressed rifles, and short-barreled setups, this all-in-one performance kit combines Geissele’s flagship Reliability Enhanced Bolt Carrier Group (REBCG) with a Super 42 Braided Wire Recoil Spring and a Silver-anodized H2 Heavy Buffer.

At the core of the REK is the Geissele REBCG, precision-machined from ultra-dense Carpenter 158+ steel and treated with Nanoweapon—a proprietary military-grade DLC (Diamond-Like Carbon) coating that exhibits extreme surface hardness, slick lubricity, and effortless carbon cleanup. The bolt assembly features stress-relieved lug radius cuts, dual-spring extractor support, and an optimized gas key interface designed to prevent bolt shearing and gas leaks under sustained rapid fire. The included Super 42 spring utilizes three braided wire strands coiled together to absorb recoil harmonics, eliminate internal buffer "spring twang," and increase return-to-battery seating force.

Paired with the silver-anodized H2 heavy buffer (approx. 4.6 oz), the Geissele REK delays bolt unlocking, dampens severe gas impulses from suppressed shooting, and significantly reduces felt recoil. Backed by Geissele’s unyielding commitment to combat-grade manufacturing, this drop-in kit provides the ultimate drive-system foundation for modern AR-15 builds.

Armorer Bench Notes & Real-World Staging Guidance:
Fitment Matrix: Fits standard Mil-Spec AR-15, M4, and carbine-length receiver extensions chambered in 5.56 NATO, .223 Remington, .300 AAC Blackout, and 6.5 Grendel. (Note: The included Super 42 braided wire spring is specifically contoured to fit the proprietary smaller inner diameter of the included Geissele H2 buffer housing; do NOT attempt to use a standard Mil-Spec carbine buffer with the Super 42 spring).

1. Perform a complete firearm safety check: drop the magazine, pull the charging handle rearward, lock the action open, and visually inspect the chamber to verify zero live rounds are present.
2. Remove the existing bolt carrier group, standard buffer, and standard carbine recoil spring from your upper and lower receivers.
3. Depress the buffer retainer pin and slide the Geissele Super 42 Braided Wire Spring and H2 Buffer assembly together into the carbine receiver extension tube until captured by the retainer pin.
4. Apply a thin layer of high-grade gun oil to the exterior friction points and gas rings of the Geissele Reliability Enhanced Bolt Carrier Group (REBCG).
5. Slide the REBCG and charging handle into the upper receiver, verifying smooth cam pin rotation and full forward battery seating.
6. Reassemble the upper and lower receivers, then perform a dry-function test, bolt lockback test, and charging cycle check before range staging.

Key Features

• Reliability Enhanced Bolt Carrier Group (REBCG): Forged from Carpenter 158+ steel with Nanoweapon DLC coating for unmatched surface durability and effortless cleaning.
• Super 42 Braided Wire Recoil Spring: Multi-strand braided spring architecture absorbs structural vibration, eliminates buffer spring "twang," and ensures positive lockup.
• Silver Anodized H2 Heavy Buffer (4.6 oz): Calibrated buffer mass smooths out overgassed systems, mitigates felt recoil, and delays bolt unlocking on suppressed rifles.
• Nanoweapon DLC Coating: Advanced thin-film coating provides extreme surface hardness and corrosion resistance under high thermal stress.
• Enhanced Bolt Lug Geometry: Stress-relieved bolt radius prevents lug shearing under high chamber pressures and sustained rapid-fire cycles.
• Complete Drop-In Upgrade Kit: Combines bolt carrier, bolt, firing pin, cam pin, gas key, Super 42 spring, and H2 buffer in one unified factory pack.

Product Specifications

• Brand: Geissele Automatics
• Model/Series: Reliability Enhancement Kit (REK) H2
• MPN / SKU: 05-492-H2
• UPC: 817953026724
• Caliber Compatibility: 5.56 NATO / .223 Rem / .300 BLK / 6.5 Grendel
• Platform Compatibility: AR-15 / M4 (Carbine Receiver Extensions)
• BCG Material / Coating: Carpenter 158+ Steel / Nanoweapon DLC
• Buffer Weight: H2 (Approx. 4.6 oz) - Silver Anodized Finish
• Spring Type: Geissele Super 42 Braided Wire Spring
• Total Kit Weight: Approx. 18.2 oz
• Country of Origin: USA