I am seeking a good long range pronghorn, whitetail and muley cartridge for my wife. She is a very small-framed woman, so I would prefer a cartridge that is not going to be too punishing for her to shoot effectively. I have really come to admire the 6.5 mm rounds (6.5x55 Swede or .260 Rem), but I am also considering the .25-06. When I mention 'long range', I am assuming 600 yards as a max range, as opposed to 1000 range match shooting. Help would be appreciated.