The commercial version of the 257 Roberts was released by Remington in 1934 chambered in their Model 30 bolt action rifle. The original cartridge was designed by H. H. Roberts (a well know experimenter and gun writer during the 1920's and 30's) and is based on the 7 x 57 Mauser necked down. Remington changed the Roberts shoulder angle from 15 degrees to 20 degrees. The name of the cartridge was adopted to honor its original developer. The 257 Roberts has often been referred to as the "most useful rifle cartridge ever developed". That is not very far wrong. It is suitable for a wide range of hunting under a variety of conditions. As a long range varmint cartridge, it is as good as they come, being only slightly inferior to the newer 6mm's. On deer, antelope, black bear, sheep or goat it is as good as any other cartridge available. Naturally, it is not as powerful as the 270 Winchester or 30-06 Springfield but has ample power for the game mentioned at all practical ranges. 

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