In Vietnam, I watched an ARVN Ranger execute 7 VC with a Ruger .22. Straight-on head shots. All dropped like rocks, followed by little fountains of blood spurting up from the wounds. A ricochet off a skull, of course, is a different matter, but any penetrating brain wound to the cerebral cortex or brain stem is an instantaneous exit from this world. A shot in or near the heart will turn you off like a light switch from disruption/stoppage of the heart's electrical pattern. Not from tissue damage. Have seen that, too. One of my grunt buddies took a stray M-16 round to his right kneecap and went down like a log before I could blink. We have to give him 2 ampules of morphine before the medevac arrived. I've seen other grunts cover up their groins before they cover their heads, that's probably psychological. Bottom line, if you can't muster the presence of mind for a clean head or chest shot under stress, forget about carrying a pistol and hire a bodyguard.