https://www.youtube.com/watch?v=b4sVQ_ZwI04
I know that my very small EDC pistol even with good ammo is NOT effective enough, which is why I carry a spare mag and have no issues firing until the threat is ended, even if I need to reload.
I am slowly figuring out what I want to carry in a chest rig if I'm in bear territory (while hiking), and I am leaning towards 10mm for capacity and ease of reloading. I love how versatile 10mm can be, too. Pud loads to skull crackers.