AlaskaMagnum has a point. Robert Raurk killed cape buffalo with an 06. So it can do the job. But would you really want to be the trigger man on that job? I have seen Elk that were killed with a 250 Savage. I read in a book KILLER BEARS that an Inuitup in Alaska killed a Grizzly with a .22LR. He didn't have a choice but, MAN!!! I would go with a 30-06 at least for Moose. Hornady Light magnums are stepping on the heels of the 300. Win. Mag. And you don't want to swim after him. But if it is what you have at hand, it will do. But use good ammo with a quallity bullet, and make that shot count.