I have harvested elk & moosewith .277&up without a hitch the reality is start with a solid constructed bullet and put it where it counts you'll collect your animal.TheCal/Cartridge I currently use (also has accounted for the most of each species):.284 - 7mm rem mag.

That said if I had to pickoneelk/moose cartridge it would be the .338wm, seems to me to be tailor made for the larger game in NA.