RE: bullet size for elk hunt
I would definately stay above oraround 350. I had been using the 405 powerbelt, but last year used the 338 platinum powerbelt. Haven't killed any game with them yet though. If my Omega shoot them accurately, I would be using the NE 460.
One note of caution. Bullets that are more than twice as long as they are in diameter are not legal in Colorado. In a 50 caliber, it you get much over the 460 I think you would be possibly going over that requirement.