necking up a 7 mm remington magnum case, necking down a .338 winchester magnum case, or running .300 winchester magnum cases through a full-length sizing die. since the first two options leave the brass a bit short, the third is generally considered to be the best option. ammunition for this caliber is not cheap (typically us$50–60 for 20 cartridges) and as such it is mainly of interest only to handloaders who own a rifle chambered in this caliber. the cartridge makes use of a belted case for headspacing.