For 600 to 700 yards with well over 2000 ft/lb kill power at that range I'd go with my custom Bergarra Wilderness 300PRC. SS Ceracoted 26", timney 2 stage, 8 or 9 twist, using 225ELD, 230 ATIPS or 245 Elite, Hornady Brass (neck turned), BR or Fed match primers, 3000fps with H1000 or N570 or...