I've always leaned towards 180gr for elk but I sat in on a seminar put on by a professional caller who shared some of hunting tactic and talked about different calibers. His opinion for 3006 on elk is 150 gr due to the ballistics of it. He has hunted elk a lot more then I have.

I agree with Spaniel. What ever you decide to shoot, practice and learn what the round you are shooting will do at all the distances you plan to shoot.