The common sense rational of one cartridge for both firearms was epitomised by the .44-40 in the Colt SAA and 1873/1892 Winchesters. Ken Waters did a .357 for pistol and carbine for HANDLOADING which is reprinted in the two volume collection of those articles. There isn't one outstanding load that performs well in both systems. The useable range is dictated by the cartridge performance more than the small, but usefull increase in velocity and accuracy from a carbine. Several of the fine old rook rifles were chambered in essentially a .38 special and have been successfully rechambered for .357 as well. If your moivng into rifles, I'd get a .22 It's so versatile and of value for training it's amost a 'given.'