Outerwild AR15 Saltwater Arms Barrel AR Platform 5.56NATO 7.5in Government Pistol Length 1-7 Twist 1/2x28 Thread Stainless Steel. They are drilled reamed rifled contoured and assembled at our Lake Zurich Illinois state-of-the-art facility. The Outerwild stainless steel barrels are corrosion-resistant and compatible with most AR platform rifles. Specifications for Outerwild AR15 Saltwater Arms 5.56NATO Barrel: Manufacturer: Outerwild Color: Stainless Steel Finish: Anodize Fabric/Material: 7075-T6 Aluminum Caliber: 9mm Luger Barrel Profile: Government Gas Block Journal Size-Diameter: .750 in Threads per Inch: 1/2x28 Barrel Twist Rate: 1-7 Barrel Material: 416R Stainless Steel Flutes: No Gun Make: AR Platform Gun Model: AR-15 Package Contents: Outerwild AR15 Saltwater Arms 5.56NATO Barrel What firearm models does the manufacturer say Outerwild AR15 Saltwater Arms 5.56NATO Barrel is compatible with? The manufacturer says that Outerwild AR15 Saltwater Arms 5.56NATO Barrel is compatible with AR-15Outerwild 1101-1100-001-O: AR15 Saltwater Arms Barrel AR Platform 5.56NATO 7.5in Government Pistol Length 1-7 Twist 1/2x28 Thread Stainless Steel