Well I say that if it is legal then its up to him what he wants to do. Of course this is either a joke or a nutty but generally I like nutties. Maybe it is legaleven if it does not sounds like it? Can he ensure safety? If so, then it is kind of cool.

Ive seen deer hit messier than that. Large magnums are legal and this guy has a reallybig magnum. The deer shown did probably not suffer.
The running question is ifthe gunis accurate enough to ensure that the deer gets hit good. Giving the deer a fighting chancedoes not involve what happens after the trigger breaks. Thats just work.