SLDUCK,
If a bullet from a big game cartridge destroys an elk's heart and/or lungs, it will die. So take the rifle with which you're most confident.
I've used 160 grain Partitions out of my 7MM Rem Mag. Elk died.
A .280 Rem might just be a great way to kill elk.
I haven't seen any big game animal go very far after its topside oxygenated blood flow stopped. Nothing living remains in that condition very long without stuff necessary for oxygenating blood and pumping it topside.
