If you shoot someone chances are they won’t immediately fall down dead (a la James Bond’s elimination of bodyguards with a silenced .22 in Spectre). In fact, if you shoot someone straight through the heart they’ll have enough blood pressure to keep going for up to 30 seconds, or more.
If your attacker is hyped-up on adrenalin, they may take a ballistic licking and keep on ticking long enough to kill you dead. Which is especially dangerous if they’re terrorists slashing at you with 12″ knives.
So if you’re facing that kind of threat, indeed if you’re facing any kind of deadly threat, move! And keeping shooting until the threat ends. Realistically speaking, that won’t be one bullet. It’ll be several. How many? A bunch.
If multiple rounds center mass aren’t getting it done, a bullet to the bad guy’s command center is plan B.
Some call it the Mozambique (a.k.a, “failure to stop”). Technically speaking, a Mozambique is two to the chest, one to the head. But as I said, confirmed with TTAG’s resident war hero, the better bet is lots ‘o shots to center mass and then one to the head.
Head shots are a bitch. It’s a tiny target, and it’s usually moving. You should be too. So . . . good luck with that. But it’s well worth practicing so you have something to do if the bad guy or guys seem [temporarily] impervious to center mass perforation.
Just remember that a head shot is an aimed shot. So when you practice, go rapid fire minute-of-bad-guy then stop, at least momentarily, aim at the noggin, aim for the head and squeeze the trigger.