The TacFire BU-556-5 Pistol Upper Assembly brings compact AR-15 performance to a 5.56x45mm NATO platform in a fully built, ready-to-run package. Featuring a 5" black nitride barrel capped with an A2 flash hider, a black anodized 7075-T6 aluminum receiver, and a free-float M-LOK handguard, this complete upper is designed for smooth operation and easy accessory mounting while including a mil-spec bolt carrier group and charging handle.

Chambered in .223 Rem/5.56 NATO with a pistol-length gas system, the BU-556-5 is ideal for building a short, maneuverable AR pistol for range use, training, or general-purpose shooting where compact size is a priority. The optic-ready upper receiver and low-profile handguard provide a clean foundation for your preferred sights or red dot. Backed by TacFire’s reputation for delivering solid value and dependable performance, this upper offers a straightforward path to a quality short-barreled AR build.

• Manufacturer: TacFire
• Model: BU-556-5 Complete Upper Assembly
• Caliber: .223 Rem/5.56x45mm NATO
• Action: .223 Rem/5.56 NATO
• Barrel Length: 5"
• Optic Footprint: Optic Ready Upper Receiver
• Unique Features: Free-Float M-LOK Handguard, A2 Flash Hider, Includes Bolt Carrier Group & Charging Handle
• Threaded Barrel: Yes
• Weight: Approximately 3–3.2 lbs