ATI Outdoors Carbine Buffer Tube Kit Mil Spec Spring Buffer Locking Ring Nut Black A5102240 UPC 758152900470
Product Description
The ATI Outdoors® AR-15 Military Buffer Tube Assembly in Matte Black (SKU: A.5.10.2240 / UPC: 758152900470) is a comprehensive, duty-ready 6-position carbine receiver extension kit engineered for custom AR-15 builds, platform conversions, and tactical stock replacements. Providing all five vital recoil system components in a single matched package, this assembly eliminates the hassle of sourcing disparate lower receiver hardware and guarantees seamless mechanical interface with all standard mil-spec collapsible buttstocks.
Precision-machined from certified 6061-T6 aircraft-grade aluminum, the 6-position receiver extension tube is treated with a rugged Military Type III Class 2 hardcoat anodized finish. This military-spec surface coating provides extreme resistance to environmental oxidation, aggressive cleaning solvents, and surface galling under harsh operational conditions. Machined with precision military-diameter threads (1.185"-16 UN-2A) and a true 1.148" outer tube diameter, the tube ensures a tight, wobble-free lockup across all six length-of-pull positions when paired with modern mil-spec stocks.
Completing the kit are an impact-absorbing carbine recoil buffer, a high-tensile wound steel buffer spring, and heavy-duty military-grade E-coated steel hardware. The included steel castle nut and receiver end plate feature an anti-corrosion electro-deposition coating that provides maximum salt-spray resistance and allows for clean, authoritative armorer staking to keep your stock securely locked under sustained recoil.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Direct fit for all standard mil-spec AR-15, M4, and M16 lower receivers. Tube outer diameter is true Mil-Spec (1.148"); will NOT accept commercial-spec stocks (1.168" ID). Fits mil-spec collapsible stocks from Magpul, B5 Systems, BCM, and ATI Outdoors. Can be used on AR-10 / 308 large-frame lowers only when utilizing a dedicated short 2.5" .308 carbine buffer and .308 carbine spring.
- Ensure the host firearm is completely clear, magazine removed, and chamber visually and physically verified empty.
- Thread the E-coated castle nut onto the buffer tube with the castle notches facing the rear, followed by the receiver end plate with the alignment tab facing forward toward the receiver.
- Thread the buffer tube into the stripped lower receiver until the lip captures the buffer retainer detent and spring, ensuring the tube does not extend so far that it binds the detent pin.
- Slide the end plate forward into the receiver indexing notch, thread the castle nut hand-tight against the plate, and torque using an armorer's castle nut wrench to 38–40 ft-lbs before staking the end plate into the castle nut notch with an automatic center punch.
- Insert the carbine buffer spring and carbine recoil buffer into the tube until seated past the spring-loaded buffer retainer pin.
Key Features
- Complete 5-Piece Assembly: Includes 6-position buffer tube, carbine buffer, recoil spring, castle nut, and receiver end plate.
- True Mil-Spec Diameter (1.148" OD): Compatible with all standard mil-spec collapsible buttstocks on the market.
- 6061-T6 Billet Aluminum Tube: High-strength aerospace alloy provides exceptional structural integrity and impact resistance.
- Military Type III Hardcoat Anodize: Deep matte black military-grade finish resists scratches, weather, and solvent corrosion.
- 6-Position Length-of-Pull Adjustment: Precision-milled detent notches allow shooters to tailor stock length to armor, clothing, or stance.
- E-Coated Steel Hardware: Heavy-duty steel castle nut and end plate feature a corrosion-resistant electro-deposition coating suitable for staking.
- Standard 3.0 oz Carbine Buffer: Counteracts bolt bounce and regulates cyclic rates in standard carbine gas systems.
- High-Tensile Steel Recoil Spring: Delivers consistent, uniform forward bolt carrier group velocity and positive chamber lockup.
- Made in the USA: Proudly designed, manufactured, and quality-tested in the United States by ATI Outdoors.
Product Specifications
- Brand: ATI Outdoors®
- Model/Series: AR-15 Military Buffer Tube Assembly
- MPN / SKU: A.5.10.2240 / A5102240
- UPC: 758152900470
- Platform Compatibility: AR-15, M4, M16 (Mil-Spec Lower Receivers)
- Tube Diameter: Mil-Spec (1.148" Nominal Outer Diameter)
- Adjustment Positions: 6-Position Adjustable
- Tube Material: 6061-T6 Aircraft-Grade Aluminum
- Tube Finish: Military Type III Hardcoat Anodized Black
- Hardware Material: E-Coated Ordnance Carbon Steel (Castle Nut & End Plate)
- Buffer Type: Standard AR-15 Carbine Buffer (~3.0 oz)
- Thread Spec: 1.185"-16 UN-2A Mil-Spec Threading
- Country of Origin: United States
