Some shooters desiring to reload for obsolete rimfire cartridges alter the firearm in question to function as a centerfire, which allows them to reload. Often it is possible to reform cases from similarly sized ammunition which is in production, and this is the most economical way of obtaining brass for obscure or out-of-production calibers. Even if custom brass must be manufactured, this is often far less expensive than purchasing rare, out-of-production ammunition. Cartridges like the 56-50 Spencer, for example, are not readily obtainable in rimfire form, but can be made from shortened 50-70 cartridges or even purchased in loaded form from specialty dealers.
