reason why most people loose animals is the get antsy and dont wait a fair amount of time....people who need uber calibers have no patients to wait a hour or so.....hell i have waited 1 -2 hours with a 45-70 and a 400gr soft point

that being said,shot placement is the key!
want a deer to drop instantly everytime,shoot them in the head....practice it...cant run when the head looks like a canoe