LBE Unlimited H2 Heavy Recoil Buffer Tube Kit 6-Position Mil-Spec - Black - H2BUFKT - UPC: 706612408103
Product Description
The LBE Unlimited H2BUFKT is a complete 6-position mil-spec receiver extension kit tuned with an H2 heavy recoil buffer for AR-15 carbines, short-barreled rifles (SBRs), and suppressed firearm configurations. Designed as an all-in-one rear lower receiver mounting system, this kit provides armorers and custom rifle builders with all critical buffer system hardware, including a 6-position mil-spec receiver extension tube, carbine action spring, H2 heavy buffer, steel castle nut, and receiver end plate.
At the center of the kit is an H2 heavy recoil buffer weighing approximately 4.6 ounces, engineered with two tungsten internal weights and one steel weight. This additional mass increases reciprocating inertia, slowing down bolt carrier velocity during the unlocking cycle. The extended dwell time helps eliminate bolt bounce, smooths out felt recoil impulses, and ensures clean extraction in over-gassed direct-impingement systems, short carbine gas setups (such as 10.3" to 11.5" barrels), and rifles running suppressors with high backpressure.
The 6-position receiver extension tube is precision-machined from high-grade 7075-T6 aluminum and finished in a matte black hardcoat anodize for chemical, wear, and corrosion resistance. Standard mil-spec outer dimensions ensure universal compatibility with collapsible stocks. The kit is rounded out with a heat-treated carbine recoil spring, steel receiver end plate, and heavy-duty castle nut designed for proper torquing and staking.
*Armorer Bench Notes & Real-World Staging Guidance:
Gas System & Buffer Tuning Matrix:
• Primary Application: Over-gassed 10.3"–14.5" carbine gas systems, suppressed 5.56 NATO / .223 Rem carbines, and full-auto / rapid-fire builds.
• Stock Fitment: Mil-spec diameter 6-position tube (accepts standard mil-spec collapsible stocks).
Lower Receiver Assembly Steps:
1. Lightly coat the external threads of the aluminum buffer tube and inner bore walls with high-grade gun oil before installation.
2. Thread the castle nut and end plate onto the receiver extension, then thread the extension into the lower receiver until it captures the rear takedown pin detent and spring.
3. Depress the buffer retainer pin and spring into its lower pocket and seat the front lip of the buffer tube flush over the edge of the retainer pin.
4. Torque the castle nut to 38–40 ft-lbs using an armorers castle nut wrench, and stake the steel end plate twice into the castle nut notches using a spring-loaded center punch.
Key Features
- Complete drop-in rear lower receiver extension assembly for AR-15 platforms.
- Includes H2 heavy recoil buffer (~4.6 oz) to delay bolt unlocking and mitigate harsh recoil.
- 6-position mil-spec receiver extension tube constructed from 7075-T6 aluminum.
- Matte black hardcoat anodized finish provides scratch resistance and glare reduction.
- High-tensile carbine recoil spring delivers uniform forward bolt feeding energy.
- Includes steel receiver end plate and heavy-duty castle nut for secure installation and staking.
- Proudly manufactured in the USA by LBE Unlimited.
Product Specifications
- Brand: LBE Unlimited
- MPN / Model: H2BUFKT
- UPC: 706612408103
- Tube Type: 6-Position Mil-Spec Diameter
- Tube Material: 7075-T6 Hard-Anodized Aluminum
- Buffer Weight: H2 Heavy (~4.6 oz)
- Spring Type: Carbine Length Recoil Spring
- Hardware Included: Buffer Tube, H2 Buffer, Recoil Spring, End Plate, Castle Nut
- Platform Fitment: AR-15 / M4 Lower Receivers
