I personally have only taken deer that where pretty much totally unaware of me having a beed on them and that where totally calm before I or my son have squeezed the trigger. Bang flop. But, when I was a kid my dad used to jump deer and then shoot them when they where trying to flee. Deer that we had to track and that where typically tougher meat than the ones that went down instantly. I typically wont shoot at deer that are already on the run, we hunt in some pretty thick timber and I hate tracking deer. The caliber has never really mattered as far as whether the deer was going to fall dead on the spot or not, but the deers demeanor before you squeeze the trigger sure does.