As someone who has had intimate knowledge of aircraft in general and MD-80's and MD-11's in particular, let me say that the chances of rapid decompression by handgun fire are so minuscule, it's not worth considering. You can't do it by penetrating the skin or the windows. And I honestly can't think of a single component of a commercial aircraft that you could take out that would would make it crash. EVERYTHING important has a backup.

Add to that the fact that all police departments that I'm aware of use hollow point ammo so as to avoid "over penetration" of the intended target.

The idea that a handgun can take down an aircraft is a Hollywood myth that needs to die. It does nothing but fuel peoples irrational fear of guns, and hinder our ability to have discussions, and thus make policies, based on facts and not emotional over simplification.