What if it had run or taken a few steps and then dropped? That wouldn't have surprised you if it did but happy for you that it didn't. It could have gone either way and darn if I can explain it. Won't go into details but we had one deer that was a high shoulder shot and it was still hobbling around on three legs. Another took a high shoulder shot that also got the spine and he stumpled for about five feet and took a few more seconds to die. I made my peace with that one. ...Whaty about the high shoulder shot? Doesn't that drop them in their tracks?
The only shot that one can possibly predict that it will drop on the spot, is a brain shot and seeing what can happen, I'm not too sure on that one, now. .....
We do our best, in our own best ways and;
Be Safe !!!