WMD Guns 9mm 10.5in Government Profile 1-10 4150 CrMoV 1/2-28 Nitride Black 9MMB10.5 1-10. Barrel has a Nitromet nitrided bore treatment for longer life than chrome without affecting accuracy. Barrels are made of 4150 CrMoV chambered for 9mm button rifled with 1-10 twist rifling and machined to a standard government exterior profile. ?in-28 threads on the muzzle end. Specifications for WMD Guns 9mm 1:10 Twist Nitromet Barrel: Manufacturer: WMD Guns Color: Black Finish: Nitride Caliber: 9mm Luger Gas Block Journal Size-Diameter: .750 in Barrel Twist Rate: 1-10 Barrel Material: 4150 Chrome Moly Vanadium Gun Make: AR Platform Weight: 14 oz Condition: New Gas System Type: Blowback Gun Type: Rifle Projectile Caliber: .355 Caliber Package Contents: WMD Guns 9mm 1:10 Twist Nitromet Barrel WMD Guns 9MMB10.5 1-10: 9mm 10.5in Government Profile1:10 4150 CrMoV 1/2-28 Nitride Black