If you don't want your targets running into neighboring properties.

[Florida_Man]

I have no experience with raccoon size animals with an air rifle. Unless extreme circumstances required it, I would not attempt it in my urban neighborhood.
As for heart/lung shots on squirrels, I have found them to be as effective as head shots.

What I found was the heart and lung aim point can get you a little fleeing action. They can control the legs. The brain turns off the connection so they just plow around with the nervous system firing its last effort.