Most of the time a animal drops in its tracks from a bullet wound ,its from the shock genarated from the bullets energy being transfered to the animals spinal cord. Its my belief this is created from the bullet hitting the body and expanding to transfer its energy to the animal.If a bullet passes thur going 10,000fps or just 2000fps that has to take place at some point and time. I am not expert in bullet consruction ,but I did sleep at a holiday inn express last night!!!