Faxon Firearms Match Series 338 ARC AR-15 12.5in Upper Receiver Gunner Pistol Length 1-8 Twist 5/8x24 w/BCG Black. 5in Gunner Profile .338 ARC Barrel blends rugged reliability and precision performance in a compact format. Designed and manufactured 100percent in-house at Faxon Firearms in Cincinnati Ohio this barrel combines the durability of the Govt contour with the weight savings of a Pencil barrel for unmatched balance and handling. Constructed from 416R stainless steel with a 1:8 twist optimized for stabilizing a wide range of .338 ARC projectiles the barrel is stress-relieved air-gauge tested and finished in Black Nitride for enhanced corrosion resistance and longevity. Each barrel is individually headspaced using precision PTG gauges and Magnetic Particle Inspected (MPI) to ensure flawless performance. Specifications for Faxon Firearms Match Series 338 ARC AR-15 12.5in Upper Receiver: Manufacturer: Faxon Firearms Caliber: .338 ARC Overall Length: 21.75 in Barrel Length: 12.5 in Barrel Profile: Gunner Barrel Twist Rate: 1-8 Firearms Threads Per Inch: 5/8x24 Muzzle Device: No Color: Black Gun Model: AR-15 Fabric/Material: Stainless Steel Handguard Length: 10.75 in Gun Make: AR Platform Flutes: No Package Contents: Faxon Firearms Match Series 338 ARC AR-15 12.5in Upper Receiver What firearm models does the manufacturer say Faxon Firearms Match Series 338 ARC AR-15 12.5in Upper Receiver is compatible with? The manufacturer suggests that Faxon Firearms Match Series 338 ARC AR-15 12.5in Upper Receiver is compatible with AR-15Faxon Firearms FX-URG-M33A075-C-SR: Match Series 338 ARC AR-15 12.5in Upper Receiver Gunner Pistol Length 1-8 Twist 5/8x24 w/BCG Black