This is gonna sound crazy, but empty gun of cartridges (check, check & re-check) rack the slide (and make ready as if you were gonna dry fire) place it back in place hammer back of course. Now get a nice long #2 pencil with a nice big eraser and insert it down the barrel eraser first. Aim at the ceiling (preferably don't have a point on pencil) and fire. If the pencil doesn't go flying through room you got a potential problem. If it does your fine. It seems silly and a lot of people will laugh or the ones under 40 yrs old will say Nooooo! I was taught this in the police academy in the 80's after they found firing a few rounds after cleaning (yes we did that to & it is now coming back in vogue) was not cost effective. Do this after cleaning to make sure everything is put back together right, there is no damage to firing pin, and it will fire. This will not work on striker fired pistols!