I had a ND today

[SideShow Bob]

Did you actually eyeball the ammo as you loaded the magazine to spot bad cases, set backed bullets, and most important, protruding primers ?
Or, when was the last time you cleaned the pistol ? And if cleaned, did you push the firing pin in too far when reinstalling the firing pin stop and lodge it in the hole in the breach face ?

You didn't recently have any trigger work done to lighten the pull did you?

I bet the next time you pull the slide back to chamber a round you will have the muzzle pointed down range in a safe direction.

Since you are in Thornton, get ahold of Bert with BP Tactical to give your pistol the once over to see if there is any mechanical problems.