Many elk have fallen to smaller calibers. The smaller 7mm-08 is very popular with elk hunters and if it'll handle them, the 308 is better. The 308 and 165 bullets is great. As for 150's, I've killed a lot of elk with 150's from a 270.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.