I wouldn't try it for deer, even if it was legal - as it is here. Actually, any ML is legal for moose, elk, grizzly's, whatever, but not buffalo. Yeah - game branch is not too bright which is what happens with bureaucrats make the rules.
If someone showed up here in camp to hunt moose with a .40, I would not guide him unless he acquiesced to using one of my rifles.
Actually, big game is why I have .58, 20 bore smooth and best yet, a .69 calibre moose killing rifle. The .50 will work, but will work better as a rendezvous rifle - where 'struttin' in part and parcel of the experience.