[G_Wen]

http://www.firearmstactical.com/pdf/fbi-hwfe.pdf

Here's a PDF analyzing the effectiveness of firearms. It was written in 1989 so it is a bit out of date. Perhaps someone with more experience with firearms can check to see if the article is still relevant.

It does confirm that "Even if the heart is instantly destroyed, there is sufficient oxygen in the brain to support full and complete voluntary action for 10-15 seconds".

[jarin]

So there might be something to the idea that you stay conscious for a bit after getting beheaded?

[archon]

Supposedly, the chemist Antoine Lavoisier[1], who was beheaded during the French Revolution, asked his assistant to quickly retrieve his head after the blade fell and count how long he could blink his eyes. The head blinked in the range of 12-15 times.

[1]: http://en.wikipedia.org/wiki/Antoine_Lavoisier

[archon]

All I can offer is another anecdote, not a more recent study, but in the self-defense courses I've taken over the past couple years, my instructor has stressed that a shooting is always a gamble.

"The only way to ensure instantaneous incapacitation is to destroy enough important brain matter. Do you want to aim at a 2-inch square target on your opponent's fast-moving head, or do you want to take your chances aiming for center mass?"

So I don't know if this instructor is an oddball or if he represents the current popularly held wisdom, but this instructor at least acknowledges that the effects of gunshot wounds are extremely unpredictable, which lines up with that study.