@dora_da_destroyer also stopping power with handguns is essentially all irrelevant now. Advancements in modern ammunition have rendered all 3 of the main pistol certitudes (9mm, .45, and .40) all more or less the same. Most people these days carry 9mm because they can carry the most ammo. .45 is falling out of favor because it's got a lot of stopping power, but if you've got 8 rounds and even get attacked by just ONE person, and between the stress and adrenaline you only land 3 or 4 those, that it no guarantee the person is going to stop trying to murder you. As I said, landing bullets on a threat until they stop trying to kill you is the most important thing if someone is trying to kill you, and it's better to land more small bullets than it is to land a few marginally bigger bullets. 9mm is by far the most popular handgun ammo in the world right no for this reason, and technology advancements have made its stopping power not significantly worse than 40 or 45. .40 is the cartridge for indecisive people that want the best of the both worlds and can't stop straddling the fence, and they get the worst of each.
I know this is morbid stuff to talk about, but it's important.