I think most of the regular XTPs are supposed to start expanding at 800fps or so.
You should be fine. High velocity in ML deer loads is as much about trajectory as power, although I usually have a just-in-case bear tag in my pocket.
Hope you can give that young lady plenty of practice so she'll be confident. It's a good thing you're doing for her. Maybe someday she'll take her old Grandpa hunting!
