Daniel Defense 16176018 5.56mm .223/5.56 NATO 10.3\" Black Heavy Phosphate barrel. This barrel features a heavy phosphate exterior coating in black and chrome lining for durability. Government profile. Caliber is 5.56 NATO / .223. Barrel length 10.3 inches, twist 1:7. AR-15 firearm fit. Not shippable to California, Illinois, or Washington. Weight 1.35 lbs.