Winchester Unprimed Brass Cases 375 Win (Big Bore) (50pk)Winchester Reloading Brass is manufactured to extremely tight tolerances to ensure smooth feeding and positive chambering. Consistent case to case weight and capacity delivers outstanding accuracy. Winchester's high quality, durable brass can be reloaded several times. New, unprimed brass. This is not loaded ammunition. Preparation: Due to the manufacturing process and or shipping, case mouths may not be perfectly round. To ensure a round case mouth,