Elk are tougher; as others have mentioned, they take off at the sound of the shot and go some distance. They also must be hit well; shoulder or boiler room shot with a properly constructed bullet.

Moose aren' t as tough; my late father brought down two moose with well placed shots using a .243 Winchester; both were one shot kills. I' m more comfortable using a .30-06 or better for moose as there are grizzly in the same territory.