don't take this as an offense, but I have the impression that you haven't thought enough about guns yet. If you have one, undload it, store it safely and think for a while - or give it away.
Pull a gun only if you are ready and willing to kill, then the 4 rules...
If you want a non-lethal weapon thats great. Get a taser. Theres an impressive video in another forum here.
If you need a gun you will be extremely lucky to have the opportunity to fire one shot. This one rather be a hit and effective. If I only saw you aming at me I'd draw and shoot instantly (what would I have to loose at gunpoint?).
If you don't want to hit, dont draw. It's safer for you and those behind you.
Si vis pacem - para bellum
If you want peace - prepare for war