I could have taken him out with a .22 behind the ear.
Mastoid bone. Small but thin...
I remember several years ago a young woman was shot behind the ear with a .22 pistol execution style in a Seattle park.
It just knocked her out for a while. When she woke up with a little blood running down her neck, she called the cops and they picked up the boyfriend who shot her.
I guess if you're going to try to kill somebody with a little noisemaker, you'd better be sure you got the job done before you run off for a beer.