” I’ve learned that .25acp, .32acp, .38 spec also are weak rounds that can’t hurt anybody through my extensive research on the internet. Oh yeah. Apparently 9mm also.”
It all depends on how fast you want them to bleed out.
If you have an half hour, .22 will do the job just fine.
10 seconds or less? You need a lot more power and diameter.
Unless you have good shot placement. Then a 22 is as good as anything. More people are killed by 22lr than anything else.