The key to Swampmans story isn't so much the calibre, or bullet or even maybe shot placement, it is that the deer was already wounded, on the run and pumped with adrenline, it is not unusal for heart shots for an animal to run, before dropping dead,
I have seen a small feral goat maybe only 60lbs in weight. After been spooked by me, shot with a .243 87gr hp by my hunting buddy, he called it good shot, tracked by my dog in tight bush , it was found dead 50yds away, its lungs were pulverised yet had run 50yds and we would not have found it without my dog.
Sometimes a good dog is worth more.
Regards Howard.