The dead elk or moose won't ever know the difference.

A 7mm mag shooting a 160 grain accubond and a 30-06 shooting a 180 grain accubond will only have about a 4 - 6 inch difference in trajectory and would be about dead even in energy levels at 400 yards.

Both of them have bullets designed for light thin skinned game and both have bullets designed for large heavy game. Use the wrong bullet in either one of them on the wrong game animal and either one could easily be seen as being explosive.