I have killed elk with a .308 and 180 gr silver tip. My gun off choice is a .300 win mag. Several of my guests on the annual elk hunt have killed their elk with a 30 - 06. One guest used a 30 - 30 with a 25-06 back up and a 30-06. The poor cow took multiple hits but went down. The key is bullet placement, the gun you are comfortable shooting and a little long range practice.