All Daniel Defense Cold Hammer Forged AR-15 Barrels are constructed of Mil-Spec 4150 Chrome Moly Vanadium Steel that is hydraulically shaped by carbide steel hammers around a precision machined mandrel to form the chamber, lands, and grooves. This Hammer Forging process creates a defect-free bore with the most consistent chamber possible, and each of Daniel Defense's barrels undergoes a Magnetic Particle Inspection (MPI) test to ensure this standard of perfection is achieved. All stripped barrels come equipped with an A4 Barrel Extension with extended M4 Feed Ramps for enhanced feeding reliability and a pre-installed locator pin. This AR-15 Pistol Barrel features a Government Profile that is slim under the handguard and heavy forward of the gas block and a Chrome Lined Chamber and Bore for enhanced wear and corrosion resistance. Its 5.56x45mm NATO Chamber is fully compatible and safe for use with both surplus mil-spec and commercial ammunition, while its 1 in 7" Rifling Twist R...