Bushmaster 0040004BLK M4 Patrolman's Upper 5.56x45mm NATO 16" Black Nitride Barrel, 7075-T6 Aluminum Black Receiver, M4 Handguard for AR-Platform

The Bushmaster 0040004BLK M4 Patrolman's Upper 5.56x45mm NATO is a complete upper receiver assembly engineered for AR-platform rifles, combining a 16-inch black nitride barrel with a precision 7075-T6 aluminum black receiver. Designed for patrol, training, and tactical operations, this upper delivers the intermediate-range performance and ergonomic balance that law enforcement and military operators expect from a proven M4-pattern configuration.

The 16-inch barrel length strikes the operational sweet spot in 5.56x45mm NATO, optimizing velocity for duty-distance engagement while maintaining the compact handling that defines the M4 platform. Black nitride coating provides corrosion resistance in field conditions—a finish preferred by agencies running weapons in variable climates and extended storage cycles. The 7075-T6 aluminum receiver is an aerospace-grade alloy that delivers superior strength-to-weight characteristics while meeting milspec dimensional tolerances, ensuring compatibility with standard lower receivers and M4 handguards. The assembly weighs 5.18 lbs, typical for a mid-length gas system upper, making it suitable for both supported platform shooting and sling-mounted carbine work.

This upper receiver assembly is built for users who need a documented, mil-pattern M4 upper for duty, qualification, or training environments. Patrol officers, reserve military personnel, and serious civilian shooters integrating AR-platform rifles benefit from the modular flexibility of the Bushmaster design—the upper pairs with any standard lower receiver to form a complete rifle, allowing operators to customize furniture, trigger groups, and stocks to mission requirements. As a Bushmaster product, it represents established manufacturing in the tactical market, backed by a brand with recognized law enforcement and military distribution history.