.256 Newton

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, shortened [Barnes, Frank, and Amber, John T. "Cartridgs of the World" (DBI, 1972), p.76, ".256 Newton".] and 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 6.5mm 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 North American big game. [Barnes and Amber, p.76, ".256 Newton".]

References

*http://www.reloadersnest.com/frontpage.asp?CaliberID=298
*http://www.thefiringline.com/forums/archive/index.php?t-20415.html