A human being is controlled by an organic computer, connected to the organism by a centralized network of connections. Scramble the CPU or seriously disrupt that centralized network and it grinds to a halt.
...shootings are dynamic situations. You can not control the chemical enhancements of the person being shot? or body armor? or even heavy winter clothing....you can debate this till the cows come home...
One of the least talked about things in shootings is the dynamics of shooting moving targets. One can take a perfect COM aim, fire and even hit the target in the 10-ring all for naught. Why? Because (a)the angle is wrong or (b)the subject turns just as you fire and changes the body's angle.
Picture the impact at precisely the X-ring. If you are facing your opponent at a 90° angle then chances of a heart/spine hit are high. But at about 25° angle, the bullet will be headed towards the farside scapula (shoulder blade) instead of the heart.
"Stopping Power" is merely the ability of any bullet to penetrate reliably enough to reach the CNS with enough force to disrupt the signals to the rest of the body. Even without a CNS hit, a bullet that goes deep enough to do either will work fine.