Alpha Shooting Sports CHF 5.56 MK18 Pistol Barrel 10.3in Black ALP103-556NITCHF. 3" in length and chambered in 5.56 NATO 1 to 7 twist rate. QPQ Nitride finish for corossion resistance and long service life. Carbine gas port location. .077" gas port diameter Machined in house from a premium cold hammer forged 4150 chrome moly blank. Weighs 1 LB 1.9oz. pounds Extended M4 feed ramps. Muzzle threaded 1/2 - 28. 100percent made in specialized factories. Specifications for Alpha Shooting Sports CHF 5.56 NATO MK18 Pistol Barrel: Manufacturer: Alpha Shooting Sports Color: Black Finish: QPQ Nitride Additional Features: Weights 1 lb 1.9 oz .077in Gas Port Diameter 10.3in Length Muzzle Threaded 1/2-28 Extended M4 Feed Ramps 1 to 7 Twist Rate Features of Alpha Shooting Sports CHF 5.56 NATO MK18 Pistol Barrel: 10.3" in length and chambered in 5.56 NATO 1 to 7 twist rate. QPQ Nitride finish for corossion resistance and long service life. Carbine gas port location. .077" gas port diameter Machined in house from a premium cold hammer forged 4150 chrome moly blank. Weighs 1 LB 1.9oz pounds Extended M4 feed ramps. Muzzle threaded 1/2 - 28. 100percent . Package Contents: Alpha Shooting Sports CHF 5.56 NATO MK18 Pistol Barrel Alpha Shooting Sports ALP103_556NITCHF: CHF 5.56 MK18 Pistol Barrel Black 10.3in