Here legal is +.23cal. Personally for our larger sub species ofdeer,quarter bore(.257 cal) min.
As long is it is legal and you know your equipment/ability/gamethen knock yourself out.
I don't consider the head/neck area regardless of tool/cal used a good place to shoot. I have had more then a few debates on here over the years why I feel this way

. So,I'll just say my personal ethics dictate this as a no shoot situation.