I have never once been able to tell a button buck from a doe in the field in hunting conditions. I can see it happening in bow season possibly, but during gun things happen too fast and at farther distances to see the little nubs. yes they are smaller in stature, but so are young doe. and by the way, in most areas, the majority of yoy bucks are spikes or forks - not many trophy 8-10 pt. yoy running around.

ps - i would just assume shoot a mature (1.5 yr. +) deer (buck or doe), but that doesn't always happen for one reason or the other