Rainier Arms Ultramatch MOD2 .223 Wylde Barrel 20in Polished 1-7.5 Twist 1/2x28 Silver Medium. Their goal is to mass produce them to bring them to market at the most competitive prices. They wanted the best balance between accuracy while keeping the weight down as much as possible. Specifications for Rainier Arms AR-15 Ultramatch MOD2 .223 Wylde Barrel: Manufacturer: Rainier Arms Fabric/Material: Stainless Steel Caliber: .223 Wylde Barrel Length: 20 in Barrel Profile: M4 Gas System Length: Rifle Length Gas Block Journal Size-Diameter: .750 in Threads per Inch: 1/2x28 Barrel Twist Rate: 1-7.5 Flutes: Yes Gun Make: AR Platform Gun Model: AR-15 Gas System Type: Proprietary Package Contents: Rainier Arms AR-15 Ultramatch MOD2 .223 Wylde Barrel What firearm models does the manufacturer say Rainier Arms AR-15 Ultramatch MOD2 .223 Wylde Barrel is compatible with? The manufacturer suggests that Rainier Arms AR-15 Ultramatch MOD2 .223 Wylde Barrel is compatible with AR-15Rainier Arms RAB-UM2-223-20-R-FF-POL: Ultramatch MOD2 .223 Wylde Barrel 20in Polished 1-7.5 Twist 1/2x28 Silver Medium