Re: first hand exp. with the 270 win
I debated replying. Like Roy said, I am not unbiased. Nor do I have first hand experience with moose at 400. Moose is a "once in a lifetime" permit in Utah. You may only choose one "once in a lifetime" permit to apply for at a time. Moose is second on my list, after a bighorn.
First, I think you should be commended for passing a shot you weren't sure of. Personally, I would have had no doubts taking that shot, or one much further.
As for personal experience, I have taken a fair amount of game with handguns, and my bow. I think much of the debate over wether a caliber is big enough for a given animal at a given range is just another excuse to talk hunting and shooting. Certainly shouldn't get in the way in the field.
So, while I commend you for passing a shot you weren't sure of, I think you made a mistake.