I have seen a guy kill a doe with a .17.... illeagal as it is he hit her directly in the nose and she didn't flinch.... the caliber of the gun means little if you know how to use it. However move farther north where the fawns are the same size as the bucks down south in the body and theres a little more room to argue. I can't imagine shooting one of those Canada bruisers with a .243 at 150 yards but I'm sure it can be done.