Shot placement is the key on elk. Look for a bullet that can deliver at least 1500 ft lbs at 100 yds. The Nosler partitions are great bullets, but also look at the other well built bullets like the Swift A-frame, Winchester fail-safe and partition gold, and my favorite the Barnes X copper hp.

Of course, you could always use blackpowder or a shotgun with sabot slugs. Those have worked for me on my 4 elk, and none of them required a second shot.