The TacFire 4 9mm Pistol Upper Assembly is an ultra-compact, plug-and-play solution designed for sub-compact pistol caliber carbine (PCC) builds. It features a 4 4150 steel barrel with a black nitride finish for enhanced durability and a standard A2 flash hider. The 7075-T6 aluminum receiver is black hardcoat anodized and paired with a modular M-LOK free-float handguard for mounting lights or hand stops. This assembly comes fully built and includes a 9mm bolt carrier group (BCG), making it ready to be pinned onto any compatible AR-15 lower receiver or 9mm-specific lower. Note: This complete upper assembly includes the bolt carrier group and is designed specifically for 4-inch sub-compact configurations.