Ballistic Advantage BABL556014M Modern Series 223 Remington/5.56 NATO Gauge 16" QPQ Corrosion Resistant None This Ballistic Advantage M4 Profile Carbine Length Modern Series Barrel is machined from 4150 Chrome Moly Vanadium steel with a QPQ Corrosion Resistant Finish and QPQ coated M4 feed ramp extension.