Americans got in the 6.5mm business in 1913, with the development of Charles Newton's .256 Newton, a factory loaded cartridge for many years, up until the mid 1930's. Based on a slightly shortened .30-'06 case, the Newton would have been called a 6.5X62 in Europe.

Factory loads included a 123 grain bullet at 3103 fps. and a 140 grain bullet at 3000. The more modern 6.5X54 Brenneke and 6.5X65 RWS would not outperform it significantly with modern powders. Why Newton decided to use the British nomenclature, which reflects the bore, rather than groove diameter, remains a mystery. He did the same with other cartridges he developed, such as the .250-3000 Savage and the .22 Savage High Power (groove diameters .247" and .228", respectively).

Had Winchester not decided to use a "bastard" .277" (6.7mm) caliber (shared only with an obscure Chinese Mauser cartridge), and had offered the Newton cartridge in their Models 54 and 70 rifles, the .256 would still be going strong. It is a potent cartridge, as attested by the two deer I took with my Model 1916 Newton rifle last December.