This Spikes Tactical ST-15 Enhanced upper is a mission-ready 5.56x45mm NATO assembly built to full Mil-Spec standards. It features a 16 cold hammer forged steel barrel with a black phosphate finish and a 1:7 twist. The 7075-T6 aluminum receiver houses a Mil-Spec M16 bolt carrier group and a mid-length gas system for smoother cycling. Equipped with a 12 SAR3 M-LOK free-float handguard and an F-marked A2 front sight, this 4 lbs unit provides duty-grade performance and accuracy for any AR-15 platform. Note: This complete upper features a mid-length gas system which typically offers reduced felt recoil compared to carbine-length systems.