RE: knockdown power... fact or myth?
Absolutely no way a rifle did that to something the weight of a deer. She probably jumped when he shot her and did a flip. Deer can do some crazy things when shot, and they can jump very high.
I think most of the time when someone thinks they see a deer get knocked off from their feet they had a spasm or jumped when the bullet hit them. I have shot one with a bow and it did the same thing, and there is no way a bow has that much energy, especially mine.
Paul