Originally Posted by KalashnikovJosh
Don't expect any typical service handgun caliber to be effective at immediate incapacitation unless the CNS is hit.
BY CNS I will assume you mean brain and spinal column. With that in mind please allow me to add some info.
Unless you get a brain stem or high spinal column hit immediate incapacitation is an extremely unlikely event. A brain shot or anything below a cervical vertebra hit will normally not cause immediate incapacitation in most handgun calibers, and I stress the word "immediate". In fact, with the majority of handgun calibers and commonly used bullet design calvarium penetration is not at all a sure thing. Strike angle and the area of the skull as well as caliber and projectile design are huge factors in determining whether your shot will even penetrate to the brain.
While odds of incapacitation vary with organ system and degree of organ destruction, no other shot with a common handgun caliber will give you instant incapacitation. That includes totally destroying the heart since the brain will still have enough oxygenated blood to function at a normal level for at least 30 seconds.
In other words, if you want a shot that will totally incapacitate the bad guy right this second your aim point from straight on is a little bit larger than the Surgeon General's warning side of a pack of Marlboro Light 100's. Now all you need is a good knowledge of skeletal anatomy, a very steady hand, and a bullet that will penetrate enough to get there.