RE: What is best 30-06 ammo for Elk
Any rifle that is originally chambered for the 30-06 will handle the HE loads. Certain military conversions (receivers) are not designed to handle the pressures that any 30-06 cartridge generates. Federal is able to generate higher velocites with out increasing chamber pressures beyond SAAMI specs with their HE loads. If I remember corectly it is from a dual powder base or something like that.
The exception being semi auto rifles. Do not use the HE loads in autos.
The 180 grain Nosler partition would be about as good a choice as you could get provided they are accurate out of your rifle. If not try the TBBC, A-frame, failsafe, partition gold, Barnes-X.