[@Dazsos] Well you've gotta look on the opposite side of things. Humans are notoriously hard to kill, especially the tough ones. A human can be riddled with so many bullet holes that they look like swiss cheese. As long as it doesn't irreparably damage a vital organ, they can keep kicking. And even then.

Humans can survive on half a brain, a single lung, one kidney, half a liver, one kidney, so on and so forth. 

Guns are super lethal.
Humans are designed to survive lethal things.