A Swiss target cartridge originally for single-shot, Martini-action rifles. The 10,3x60R is identical to the obsolete British 450/400 (2 3/8-inch) black-powder Express. This cartridge is in the same class as the 405 Winchester and would do for any North American big game at short to medium range. This cartridge is still popular in Switzerland and guns and ammunition are still manufactured in Switzerland and in Germany by RWS. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.