I have close family that is LEO. Very few incidents of needing to use a firearm in duty. But there are those stories that poke through where you go "but how?" I saw a statistic somewhere (I think it was a reputable source) that 70%+ of all those shot with a handgun live (there was no discussion on round quantity, trauma level, distance etc.). It would appear that rapid loss of blood pressure is what most people describe as "stopping power," and the only effective way to end a mortal threat when it's clear that the experience of pain and trauma isn't enough to act as a deterrent.
Basically, you get someone who is on a drug(s) that jacks up the dopamine and norepinephrine levels, and you have potent recipe for someone whose neuro-chemical signals are hijacked and they can't physiologically interpret a gunshot wound like a normal human.
Then, you get this guy who wasn't on drugs, accidentally shot by the police 16 times and is alive.
Man mistakenly shot by police: ‘Sometimes they make mistakes’
I think there's enough evidence across the board to say that handgun trauma is variable, and without the right placement and circumstances, can lack "stopping power."