Manufactured 100% in-house from gun-barrel-quality bar-stock, the Match Series starts with 416-R in 5R rifling. 5R is a hybrid rifling, with lands opposite grooves and reduced sharp angles that reduces jacket deformation increasing velocity and easy cleaning. After rigorous testing, the barrels are Nitride treated inside and out, locking in the bore, improving barrel life, and keeping the elements at bay.The extension is coated in Nickel Teflon which maintains incredible dry lubricity, corrosion resistance, and with the coating, tightens up fit between the extension and receiver - again improving upon accuracy. Combined, the Match Series of barrels are ready for when duty calls or the buzzer beeps with unrivaled performance value. Barrel Material: 416R Certified Gun Barrel Quality Stainless Steel Barrel Type: 5R Button Rifled Barrel Caliber: 6.5 Grendel, SAAMI Chamber (.136 Co-Bore On Bolt) Barrel Twist: 1:8 Barrel Length: 16 Barrel Profile: Gunner Barrel Gas System: Mid Inside Finish: Salt Bath Nitride Outside Finish: Salt Bath Nitride Muzzle Thread:5/8-24 TPI (Threads Per Inch) Gas Block Diameter: .750 Gas Block Journal Length: 1.9 Barrel Extension: M4, Nickel Teflon Coated Weight: 1.53 lbs Magnetic Particle Inspected Polished 11-degree Target Crown