BSF Barrels AR-10 6.5mm Grendel Threaded AR Barrel. 416R Stainless Steel match barrel jacketed with a carbon fiber sleeve. The wrap is designed to vent heat and reduce delamination. The carbon fiber sleeve is designed to expand with the steel to maintain stiffness and light weight. Specifications include Caliber 6.5mm Grendel, Twist 1-8, Flutes Yes, Barrel Material 416R Stainless Steel, Finish Carbon Fiber, Threads 5/8x24, Barrel Profile Contour. AR Platform compatibility for AR-15 and AR-10. Length options include 12in, 14.5in Mid-Length, 16in, 18in, and 20in. Weight (base, approximate) 22 oz.