Rainier Arms Select 9mm Barrel 16in 1-10 Twist 1/2x28 Black Medium. They are able to reach our goal by sourcing a very high end barrel blank at an affordable price. Specifications for Rainier Arms AR Select 9mm Barrel: Manufacturer: Rainier Arms Color: Black Fabric/Material: Stainless Steel Caliber: 9mm Luger Gas Block Journal Size-Diameter: .750 in Threads per Inch: 1/2x28 Barrel Twist Rate: 1-10 Flutes: No Gun Make: AR Platform Gun Model: AR-15 Package Contents: Rainier Arms Select 9mm Barrel What firearm models does the manufacturer say Rainier Arms AR Select 9mm Barrel is compatible with? The manufacturer says that Rainier Arms AR Select 9mm Barrel is compatible with AR-15Rainier Arms RAB-SEL-9MM-16-NF-BLK: Select 9mm Barrel 16in 1-10 Twist 1/2x28 Black Medium