Its a matter of how far you want or need to shoot. If you go by the standard that you want or need 1500-1800 LBs ME remaining for elk, With factory loads you could use the 300 RUM out to 500 yards or a bit more, The 300 Win Mag or 300 WSM out to about 400 yards and the 308 and 30-06 out to 300 yards or a bit more. Out at 800 yards or so, none of them make the cut. The RUM with the best bullets would have dropped off to about 1200 and the rest, below a thousand. Hand loaders can increase the range of all of them a little although it may not be wise to do so. The above figures are from Hornady and use the 180 grain bullet in all calibers.