The .256 Newton rimless cartridge was developed by Charles Newton and chambered in 1913 by the Western Cartridge Company. Basically it is a 6.5/06 (a .30-06 Springfield cartridge necked down to 6.5mm) with a different shoulder angle. As such, the two cartridges are not interchangeable. It was the only commercial American designed cartridge until the advent of the .264 Winchester Magnum. Purportedly not as good for hunting as the .270 Winchester, it is still adequate for most all North American game.