Diamondback Firearms OEM Replacement Barrel FN Herstal M16 5.56x45mm NATO 16in Medium Profile Carbine-Length 1-8 Twist 1/2 x 28 Thread 4150 CrMov. Made of 4150 CMV with a carbine-length gas system. Specifications for Diamondback Firearms OEM Replacement FN Herstal M16 Carbine-Length Medium Profile Barrel: Manufacturer: Diamondback Firearms Color: Black Nitride Finish: Nitride Caliber: 5.56x45mm NATO Barrel Profile: Medium Gas System Length: Carbine Length Gas Block Journal Size-Diameter: .750 in Threads per Inch: 1/2x28 Barrel Twist Rate: 1-8 Barrel Material: 4150 CMV Steel Gun Make: FN Herstal Gun Model: M16 Package Contents: Diamondback Firearms OEM Replacement FN Herstal M16 Carbine-Length Medium Profile Barrel What firearm models does the manufacturer say Diamondback Firearms OEM Replacement FN Herstal M16 Carbine-Length Medium Profile Barrel is compatible with? The manufacturer says that Diamondback Firearms OEM Replacement FN Herstal M16 Carbine-Length Medium Profile Barrel is compatible with M16Diamondback Firearms 556C16M50B8R: OEM Replacement Barrel FN Herstal M16 5.56x45mm NATO 16in Medium Profile Carbine-Length 1-8 Twist 1/2 x 28 Thread 4150 CrMov Black Nitride