A guy from FL once said, you may not have time to go home and get you combat 45/shotgun/AR w extra mags, you may have to fight w whatever you have on you. ( I never forgot that comment)
A spare mag or HKS speedloader can mean anywhere from an additional 5 to 19 rds. Practice reloading until you can do it w/o looking and don't forget one handed. (AAR - 1986)
I am rather eclectic, Home Defense - I prefer the simplicity of 357 revolvers w those HPs just staring at the BG, they can stay loaded almost indefinitely and if one rd is bad just keep pulling the trigger for a fresh rd.
For carry, I like autos for a slimmer fit, capacity, ease of reloading etc. I rotate mags every 30 days or so.
Murphy's Law does not discriminate - I don't want to jack this thread up but an idiot proof weapon is an urban myth.
. Army's been trying for decades...