Outdoor Life publisher Eric Zinczenko just took delivery of a new long-range elk rifle, a beautiful custom Ed Brown Savanna chambered in .340 Weatherby. Hard to argue with his choice. It will certainly handle any elk that ever had the nerve to hang out on the other side of the canyon.
The last elk I took (with a gun) was with a rifle chambered in the anti-.340 Weatherby. I used a single-shot .260 Remington. I shot the bull once, at 264 yards, and it ran less than 50 yards before piling up. Those 6.5mm bullets are just wonderful hunting bullets.
Anarchangel also recently weighed in on what makes for a good elk cartridge.