First, Please don't shoot at a deer while it's walking. As you learned, most of the time you are going to make a "bad" shot that is more than likely going to be too far back. Not to mention a deer's reflexes.
Your wrong Strut. Anyone can shoot a deer walking, they just need to know what there doing. I've shot a good handful walking, they were all lung and heart shots. I'll never stop a deer unless It's down right flying. I don't like alerting deer.
As for the Intent of the thread, you can make a perfect shot Wiaxle and some times they just don't bleed. Why Is that? Who really knows. It will happen no matter what BH your using. Sometimes things don't follow the rules.