Peterson Cartridge .300 RUM Unprimed Rifle Brass Features Peterson Cartridge builds its match-grade brass to a standard the company says must be held throughout the entire manufacturing process from small batch production lines through final quality control. Each .300 RUM case receives an annealed mouth and neck a heat treatment step that keeps the brass softer in that area for more consistent neck tension and extended case life across multiple reloading cycles. The cases arrive beautifully polished reflecting the attention to finish quality that runs through Peterson s production process. Multiple quality inspections throughout manufacturing are intended to catch defects before brass ever reaches a reloader s bench. This brass is unprimed and sold strictly as a reloading component not as loaded ammunition so reloaders will need to prime charge and seat bullets themselves before the brass can be fired. Peterson s stated goal is for reloaders to be able to maintain that match-grade standard all the way from the production line to the target which is the reason for the extra inspection steps during manufacturing. Consistent well-prepared brass like this is a foundation for accurate handloads since variations in case quality can directly affect velocity and group consistency downrange. For reloaders working up precision .300 RUM loads Peterson Cartridge unprimed rifle brass is available for sale at GrabAGun. Peterson Cartridge .300 RUM Unprimed Rifle Brass Specifications Manufacturer: Peterson Cartridge Caliber: .300 RUM Material: Brass Type: Unprimed Rifle Brass Rounds Per Box: 50 Available At: GrabAGun