For Elk and other heavy hided, thick boned big game, my preference would be .300 WinMag. It'll provide extra energy, bullet penetration on a big animal like elk well out to 300 yds and beyond. .30-06 is also a very good all around choice. Not quite the energy at the longer distances. But get it zero at 200 yds and know the bullet drop (charts) beyond. Stay within the ranges you're comfortable and confident at. I'd without hesitation take either .300 WM or .30-06 out for Elk and shot out to 300 yds. A very good bullet like Nosler Accubond, a quality partitioned bullet or other bullet made for heavy hide/bone animals that shoots well (accurate) out of your rifle is just as important. Best to you.