As has been stated earlier, bullet construction is more important than energy figures. Deer season '09, I had a harder time killing a deer at 30 yards with a .308 loaded with 150 grain SSTs at 2800 fps at the muzzle, than I did killing a deer at 236 yards with a .30-30 loaded with 170 grain FPs at 2184 fps at the muzzle. There was a vast difference in the amount of energy at impact, but the .30-30 still made a through and through hole, with signs of expansion. The SST blew up on impact.
The following year proved a change of bullet in the .308 was all that was needed.
With Elk, it's important to choose a bullet that will drive in deep and break things. (cough, cough, TSX, cough) Elk are more demanding of bullet integrity than a Whitetail deer.
