TacFire BU-556-7 Pistol Upper Assembly — 5.56x45mm NATO, 7" Black Nitride Barrel, Black Anodized 7075-T6 Receiver & M-LOK® Handguard — Includes Bolt Carrier Group (BU5567 | UPC 729205500503)
Build a compact, reliable AR pistol without the parts hunt. The TacFire BU-556-7 Pistol Upper Assembly delivers a turnkey top end for your AR-15, pairing a 7" black nitride barrel with a rugged black anodized 7075-T6 aluminum receiver and a slim, free-float M-LOK® handguard. Chambered in 5.56x45mm NATO, this upper ships complete with a Bolt Carrier Group (BCG), so you can mount an optic, pin it to a mil-spec lower, and head to the range with confidence.
Why Choose the TacFire BU-556-7 Upper?
Ready-to-Run Package: Comes BCG included—no scrambling for compatible carriers or headspacing variables.
Ideal 7" Barrel Length: A proven sweet spot for AR pistols—more dwell time than extreme micro barrels for smoother cycling while staying compact for CQB-style drills.
Black Nitride Barrel: Hard, corrosion-resistant finish on the bore and exterior for long service life and easier cleanup.
7075-T6 Forged Receiver: Stronger-than-6061 aluminum for a durable, duty-ready upper that holds up to high-volume training.
Free-Float M-LOK® Handguard: Low-profile rail accepts lights, QD sling cups, handstops, and switches while keeping the barrel free-floated for better POI consistency.
AR-Platform Compatibility: Designed around mil-spec AR-15 lowers for straightforward mating and reliable operation.
Key Features & Specs
Model / Part: BU-556-7 (also listed as BU5567)
UPC: 729205500503
Caliber: 5.56x45mm NATO (compatible with .223 Rem—verify ammo with your chamber)
Barrel: 7" black nitride steel, threaded muzzle (commonly 1/2x28—confirm before ordering a device)
Receiver: 7075-T6 aluminum, black anodized
Handguard: Free-float M-LOK®, slim and ventilated for cooling and cable routing
Bolt Carrier Group: Included (carrier, bolt, cam pin, firing pin, retaining pin)
Charging Handle: Not always included—verify retailer BOM
Gas System: Short configuration matched to 7" length (spec may vary by lot; check listing)
Performance You’ll Notice
Smoother Cycling: The added barrel length vs. ultra-short builds can improve gas timing and reliability with quality 5.56 ammo.
Low Maintenance: Black nitride hardens critical surfaces and resists fouling for easier wipe-downs after long sessions.
Free-Float Accuracy: By isolating the handguard from the barrel, you get steadier point of impact—useful even on compact uppers.
Accessory-Ready: Ample M-LOK® real estate for a white light, pressure pad, and handstop without adding bulk.
Ideal Use Cases
Home & Property Training: Compact OAL for maneuvering in tight spaces (follow all laws).
Range & CQB Drills: Fast handling paired with a micro red dot for practical carbine practice.
Truck/Pack Projects: Lightweight, rugged top end for mobility and emergency preparedness.
Setup, Compatibility & Build Notes
Lower Receiver: Fits most mil-spec AR-15 lowers.
Buffer System: Use a pistol-appropriate buffer and spring; short-gas builds may prefer heavier buffers—tune as needed.
Muzzle Devices: Confirm thread pitch before installing a brake, flash hider, or suppressor mount; re-torque and re-zero afterward.
Optics & Sights: Add BUIS or a micro red dot; verify co-witness heights with your preferred mount.
Ammo: Full-power 5.56 NATO loads often cycle short systems more reliably than lighter .223 loads.
Best Practices (Non-Instructional)
Lube & Inspect: Lightly lubricate the BCG and rails before first use; confirm gas-block and handguard screws are snug.
Ejection Pattern Check: Evaluate ejection and lock-back; tune with buffer/spring if needed for your ammo.
Cable Management: If running a light/laser, use M-LOK® cable clips or channels to avoid snags.
Zero Smart: A 25/50-yard zero works well for compact 5.56 setups; confirm holds at your typical distance.
Legal & Safety Reminder
Know and follow federal, state, and local laws regarding AR pistol configurations, barrel length, braces/stocks, NFA regulations, suppressors, and transport. Ensure any modifications keep your build compliant.
What’s in the Box*
TacFire BU-556-7 Pistol Upper Assembly — 5.56 NATO, 7" black nitride barrel
Bolt Carrier Group (BCG) — included
7075-T6 black-anodized receiver & free-float M-LOK® handguard
*Contents can vary by lot—verify the retailer’s bill of materials (e.g., charging handle, muzzle device inclusion).
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TacFire BU-556-7 Pistol Upper Assembly — 5.56x45mm NATO, 7" Black Nitride Barrel, 7075-T6 Receiver, M-LOK® Handguard, BCG Included (BU5567 | 729205500503): a compact, accessory-ready upper that blends durability, reliability, and plug-and-play convenience for your next AR pistol build.
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