I was just reading information pages on the 260 rem. and the 6.5x55 swede, on the ballistic studies (Terminal Ballistics Research) website. I am reading as much as I can about these two cartridges, since I am seriously contemplating either of these rounds for a long-range pronghorn, whitetail/muley rifle. In the articles I read, regarding each round, the author (name was not given) stated that each of these 6.5 rounds gave poor killing power beyond 200-250 yards. He actually stated that their "killing power" was much closer to that of the 30-30, instead of the 270 win., for which they are often compared to. All I have read regarding these two rounds, up to this point, indicates that the 260, the swede, and the other 6.5s are deadly out to 600 yards (and beyond) within proper situations. My question is...........what am I supposed to believe? I have just become confused!! Help!