I quite pondering these things a long time ago since there is no definitive answer to what causes one deer to drop instantly and the other to run 40 or 50 yards. The only thing I need to know is that a deer hit with a decent bullet in the right place will die shortly thereafter. If he drops on the spot, fine. If he manages to make it another 50 yards, that's okay too. I've never lost a deer yet, or had one go very far, when hit in the heart/lungs area.