I'd say that under the circumstances you describe, your 9mm and your pepper spray would both be useless unless they were already in your hand. Your best bet would be get the hell out of its way (which is probably what you would instinctively do anyway) and hope for a thicket of trees you could get into that the moose couldn't get through. Moose are not only dangerous, but unpredictable, so you couldn't anticipate whether it would ignore you or charge you.