I can only assume you mean placement in the head since you just mentioned a failed heart shot?
Any hunter should know that body placement and stopping power sometimes dont even matter because I must have heard a thousand different stories about how a deer ran 150 yards shot in the heart. A side headshot on a deer usually results in at least one lung being shot also.
The one story I never heard is how a deer, or anything, ran anywhere after a clean shot to the head.
If the goal is really stopping power then a smaller more accurate weapon seems like the answer.
nah man, people are animals too
Mortally wounded aunt still saves her nephew, 8: Carries boy to safety as bullets fly in Brooklyn
http://www.nydailynews.com/news/crime/mortally-wounded-aunt-saves-nephew-8-carries-boy-safety-bullets-fly-brooklyn-article-1.399887