TacFire BU55610 Pistol Upper Assembly 556x45mm NATO 10 Inch Nitride Barrel MLOK Handguard with BCG UPC 729205518300
Product Description
The TacFire® 10" 5.56x45mm NATO Pistol Upper Assembly with Bolt Carrier Group (SKU: BU55610 / UPC: 729205518300) delivers a turn-key, battle-ready front-end solution engineered specifically for ultra-compact defensive carbines, truck guns, and AR-15 pistol builds. Outfitted complete from the factory with a dedicated bolt carrier group and charging handle, this drop-in assembly eliminates assembly guesswork, providing high cyclic reliability, rigid rail indexing, and rapid target transitions right out of the box.
The foundation of the receiver is precision-forged from mil-spec 7075-T6 aluminum and protected by a non-reflective MIL-A-8625 Type III Class 2 hardcoat anodized finish that shields internal carrier pathways against carbon abrasion, extreme heat, and harsh cleaning chemicals. Seated within is a 10-inch 4150 Chrome Moly Vanadium (CMV) steel barrel processed with an advanced Salt Bath Nitride / QPQ Melonite treatment. This metallurgical surface conversion hardens the bore against throat erosion and corrosion while delivering exceptional velocity preservation. The 1:7" twist rate stabilizes heavy tactical projectiles up to 77 grains, and the 1/2x28 TPI muzzle interface accommodates standard .223/5.56 flash hiders, muzzle brakes, and suppressor adapters.
Enclosing the carbine gas system is a free-floating 6061-T6 aluminum handguard engineered with an ergonomic slimline profile and full M-LOK® attachment modularity. Eliminating handguard-to-barrel contact ensures zero point-of-impact shift when running heavy weapon lights, barricade rests, or handstops. A full-length Mil-Spec 1913 Picatinny top rail extends uninterrupted from the upper receiver to the end of the handguard, providing an uncompromising zero-retention platform for reflex sights, holographic optics, magnifiers, and backup iron sights.
*Armorer Bench Notes & Real-World Staging Guidance:*
Fitment Matrix: Compatible with all standard Mil-Spec AR-15 lower receivers. CRITICAL: Barrel length is 10.0 inches. Legally compliant strictly for dedicated AR pistol configurations or registered NFA Form 1/4 Short-Barreled Rifles (SBR). Never assemble onto a lower receiver with a buttstock attached unless legally registered. Standard 1/2x28 TPI muzzle threads; torque muzzle accessories to 20–25 ft-lbs using precision shims if mounting sound suppressors. Includes factory-inspected BCG and standard charging handle.
- Ensure the host firearm lower receiver is completely clear, magazine well verified empty, and firing path clear prior to assembly or maintenance.
- Separate the included bolt carrier group and charging handle, wipe down shipping oils, and apply high-viscosity synthetic lubricant to the bolt carrier friction rails, cam pin, and gas rings.
- Reinsert the charging handle and BCG into the receiver raceway, seat fully into battery, and verify seamless alignment against the M4 barrel extension feed ramps.
- Align the upper assembly's front pivot pin lug into your host AR-15 lower receiver, press the front takedown pin fully home, pivot closed, and engage the rear takedown pin.
- Cycle the charging handle manually several times, confirm positive bolt catch engagement on an empty magazine, and execute a comprehensive dry-fire function check of the trigger reset and safety selector.
Key Features
- Factory-Complete Package: Includes full Mil-Spec bolt carrier group and standard charging handle for immediate drop-in functionality.
- 4150 CMV Nitride Barrel: Salt Bath Nitride (QPQ) treated 10" barrel maximizes bore longevity, thermal resistance, and environmental durability.
- 1:7" Twist Rate: Precision button rifling stabilizes standard 55gr/62gr loads along with heavier 75gr and 77gr match and defensive cartridges.
- Free-Float M-LOK® Handguard: Rigid 6061-T6 aluminum handguard provides modular accessory mounting without transferring stress to the barrel.
- Forged 7075-T6 Receiver: Mil-Spec forged receiver fitted with forward assist, dust cover assembly, and precision-cut M4 feed ramps.
- Standard 1/2x28 Thread Pitch: Features an A2 flash hider and accepts all standard 5.56 NATO muzzle brakes, compensators, and suppressor mounts.
Product Specifications
- Brand: TacFire®
- Model/Series: 10" 5.56x45mm NATO Complete Pistol Upper Assembly with BCG
- MPN / SKU: BU55610 / BU-556-10
- UPC: 729205518300
- Caliber: 5.56x45mm NATO / .223 Remington
- Barrel Length: 10.0 Inches
- Barrel Material: 4150 Chrome Moly Vanadium (CMV) Steel
- Barrel Finish: Salt Bath Nitride / QPQ Melonite
- Barrel Twist Rate: 1:7"
- Gas System Length: Carbine-Length (.750" Gas Block Journal)
- Muzzle Thread Pitch: 1/2x28 TPI
- Bolt Carrier Group: Included (8620 Steel Carrier, Properly Staked Gas Key)
- Charging Handle: Included (Mil-Spec Standard)
- Receiver Material: Forged 7075-T6 Aluminum
- Receiver Finish: MIL-A-8625 Type III Class 2 Hardcoat Anodized
- Handguard: Free-Float Slim M-LOK® 6061-T6 Aluminum
- Platform Compatibility: Standard Mil-Spec AR-15 Lower Receivers
- Country of Origin: USA / Imported Components
