The momentum of the 600N.E. is less than a big hammer when you swing him on the elephants skull! The elephant just will gett angry.

Even my the momentum of my 8x68S that hit a bull of a highland close to the brain deafened the bul just about 10 seconds and that is not a big bore! The place of the bullet and the penetration is the main thing for a bGr cobined with the biggest Diameter you can handle.

Here you can calculate the penetration of the different cartridges:
http://home.snafu.de/l.moeller/

Look for Poncelot!