Have you hunted elk before? You don't NEED either of these calibers to kill elk, even at some pretty long ranges. That said, there are some really good LR rifles available now from this site. Have you looked at the LongRangeRifles tab here? There is a .338 edge available now, and a .300 RUM that will be ready soon. If you're going after one of these big boys, might as well get it in a purpose-built rifle that can make the most of the caliber. I have a custom LR rifle coming in a 7 Rem mag. I would feel confident shooting elk out to 1K with this round, assuming broad side shot angle, etc. I will admit though, I am already thinking a .338 next for the high BC bullets available.