According to other posters, elk are huge and here's what you need:

http://www.vce.com/grable.html

Geeze, I don't know, that atomic cannon is only a 280, just a small bore. LOL. For the elk rifle question, I use a 8mm Rem Mag with 220 gr bullets or a 340 weatherby Mag with 250 gr bullets. Not much difference between the two. 8mm shoots a little flatter. In the breaks where it's thick, I agree with the previous post and use a 350 Rem Mag (ballistic clone of a 35 Whelen). I gotta get me one of those cannons though. just imagine what you could bore it out to! - Dan

Well,
Seems like the debate continues. For all of you guys who keep replying to my j4 comment - stop. As previously indicated, the j4 comment was referenced as ballistics achieved by handloading. If I used the 308 I would go with 150 gr or 165 gr nosler partions.
But I do question why not the use of a 45-70?
Reason: Research Barnes reloading data manula using their 350gr X bullets in combination with IMR 4198. You will see straight from their product data illustrating a 350gr bullet traveling just under 2000fps at 300yds with only a 6" drop in elevation.
I've heard a lot about not shooting over 300yds. and I agree with that philosophy. So, to me, shooting this type of load in a Browning 1885 low wall, I should worry more about not blowing out the shoulders......