Spikes STU5025M4S Complete Upper 5.56x45mm NATO 16" 1:7 Black Phosphate

The Spikes STU5025M4S is a complete AR-15/M4-pattern upper receiver assembly chambered in 5.56x45mm NATO, offered as a turnkey replacement upper ready to mate with any standard mil-spec AR-15 lower.

At its core is a 16" mil-spec chrome moly barrel cut to a classic M4 carbine profile with a 1:7 rifling twist, well suited to stabilizing a broad range of 5.56mm projectile weights. The barrel wears a black phosphate finish for corrosion resistance and is paired with a carbine-length gas system for reliable cycling. An F-marked A2 front sight base with A2 front sight post is pinned in place.

The upper receiver is machined from 7075-T6 aluminum and finished in black. A black M4 double head shield handguard rounds out the assembly with the familiar slim profile that accepts standard M4-pattern accessories. The complete upper ships ready to install on a mil-spec AR-15 lower (lower not included).