This 5.56 chambered 12.5" government profile modern series barrel is machined from 4150 chrome moly vanadium steel with a qpq corrosion resistant finish and qpq coated m4 feed ramp extension.Specs- 750" gas block journal, gas system length- carbine and a government profile.All nfa/atf rules apply-you may use this barrel with a lower receiver that is a registered sbr, machine gun, or pistol.Possession of this barrel along with a non-nfa lower receiver is prohibited, except when installed on a pistol configuration firearm.Caliber Or Gauge: 5.56x45mmLength: 12.50"Model: AR BarrelTwist: 1:7"Sights: NoneFinish: QPQ Corrosion ResistantType: 12.5" BarrelBarrel Type: Carbine Length Government ProfileBarrel Features: QPQ coated M4 Feed Ramp Extension