I've gotten interested in the .260 rem due to its good ballistics and low recoil. I know this is a tough question to answer, but where would you draw the line in hunting with this round? I know it would be fine for whitetails at 200yds, but would it be fine for an elk at 400 yds? I know shot placement has everything to do with it, but everything has a breaking point where it becomes almost unethical to hunt this animal at that range sort of thing. Where would you draw the line with the .260 rem shooting a 140gr bullet? Should you base the answer on energy in ft/lbs? Thanks.