We currently have a variety of very high quality 300 Blackout barrels in stock. They are Rainier Arms Select and Ultra Match barrels in 10.5″ and 14.5″ lengths and are all made from high grade stainless steel. The Select Barrels are made from the same mill as HK barrels and have polygonal rifling. The Ultra Match barrels are made from the finest Shilen blanks. Perfect for that new build.