TacFire BU-556-5 Pistol Upper Assembly — 5.56x45mm NATO, 5" Black Nitride Barrel, Black Anodized 7075-T6 Receiver & M-LOK® Handguard — Includes Bolt Carrier Group (BU5565 | UPC 659725496003)

Build a compact, reliable AR pistol with the TacFire BU-556-5 Pistol Upper Assembly. Chambered in 5.56x45mm NATO, this ready-to-run upper features a 5" black nitride barrel for durability and easy maintenance, a robust black anodized 7075-T6 aluminum receiver, and a sleek M-LOK® free-float handguard for modern accessory mounting. Best of all, it includes the Bolt Carrier Group (BCG) so you can complete your build faster and hit the range with confidence.

Why Choose the TacFire BU-556-5 Upper?

• Turnkey Upper, BCG Included: Skip the parts chase—this assembly ships with a matched bolt carrier group to simplify your build and promote consistent reliability.

• Compact 5" Barrel: Short, maneuverable length that’s ideal for confined spaces and range drills; black nitride treatment enhances corrosion resistance and fouling control.

• 7075-T6 Receiver Strength: Forged 7075-T6 aluminum delivers excellent strength-to-weight for a dependable, duty-ready upper.

• Free-Float M-LOK® Handguard: Attach lights, QD sling cups, and handstops while keeping the barrel free-floating for improved accuracy potential.

• AR-Platform Compatibility: Works with most mil-spec AR-15 lowers—perfect for pistol configurations and braced/stocked setups where legal.

Key Features & Specs

• Model/Part: BU-556-5 (also listed as BU5565)

• UPC: 659725496003

• Caliber: 5.56x45mm NATO (compatible with .223 Rem; verify your chamber/loads)

• Barrel: 5", black nitride finish for wear and corrosion resistance

• Receiver: 7075-T6 aluminum, black anodized

• Handguard: Free-float M-LOK® (low-profile, slim)

• Bolt Carrier Group: Included (carrier, bolt, cam pin, firing pin, retaining pin)

• Charging Handle: Often not included in upper-only packages—verify retailer BOM

• Muzzle: Threaded from factory on most 5.56 barrels (commonly 1/2x28—confirm thread pitch prior to purchasing a device)

• Gas System: Short configuration appropriate for the 5" barrel length (verify exact specification with seller)

Performance You’ll Notice

• Reliable Cycling: A matched BCG and properly aligned gas system support consistent operation with quality 5.56/.223 ammunition.

• Manageable Maintenance: Black nitride hardens critical surfaces and wipes clean more easily than untreated steel.

• Accessory-Ready: The M-LOK® rail gives you flexible placement for lights, pressure switches, handstops, and QD sling mounts without adding bulk.

• Free-Float Advantage: By removing handguard pressure from the barrel, you support better point-of-impact consistency—useful even on compact uppers.

Ideal Use Cases

• Home & Property Training: Short overall length for maneuverability in tight environments (obey all laws).

• Range & Skill Development: Great for CQB-style drills and dot-centric carbine practice.

• Truck/Pack Rifle Projects: Lightweight and compact for transport, with modern accessory support.

Compatibility & Build Notes

• Lower Receiver: Pairs with most mil-spec AR-15 lowers.

• Buffer System: Use a pistol-appropriate buffer and spring; short barrels can be gas-system sensitive—choose quality components.

• Muzzle Devices: Verify thread pitch before adding a brake, flash hider, or suppressor mount; re-torque and re-zero after changes.

• Optics & Sights: Add folding irons or a micro red dot on the top rail; confirm co-witness height as needed.

• Charging Handle: If not included, select an ambi or standard handle to suit your grip and light/laser placement.

Setup Tips (Non-Instructional)

1. Use Quality Ammo: Full-power 5.56 loads often run short systems better than underpowered .223.

2. Break-In & Lube: Lightly lubricate the BCG and contact points; monitor ejection pattern and make adjustments with buffers/springs if needed.

3. Torque & Check: Confirm muzzle device torque and handguard fasteners after the first range session.

4. Zero Smart: Zero your optic at 25/50 yards for practical holds at typical defensive distances.

Legal & Safety Reminder

Know your federal, state, and local laws regarding pistol builds, overall length, braces/stocks, NFA regulations, suppressors, and magazine capacities. Configure and use your AR-platform pistol in full compliance with current rules.

What’s in the Box*

• TacFire BU-556-5 Pistol Upper Assembly — 5.56 NATO, 5" black nitride barrel

• Bolt Carrier Group (BCG) — included

• M-LOK® free-float handguard, black anodized 7075-T6 receiver
  *Contents may vary by lot—always verify the retailer’s bill of materials (e.g., charging handle and muzzle device inclusion).

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TacFire BU-556-5 Pistol Upper Assembly — 5.56x45mm NATO, 5" Black Nitride Barrel, Black Anodized 7075-T6 Receiver, M-LOK® Handguard, BCG Included (BU5565 | 659725496003): a compact, accessory-ready upper that blends durability, modern ergonomics, and plug-and-play convenience for your next AR pistol build.

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