Wrong and a standard misconception. The human body can take a TON more punishment than most people believe. Not that such levels of punishment would be something most people would be willing to take to find out. Still, the human body is capable of taking far more damage than one might think and still survive.
What kills with gun shots is bleeding out, or a lucky shot to a vital organ. Vital organ would be the heart or brain for near immediate death. Other organs for a "quick" death would be the lungs for example. Otherwise, it takes time to bleed out and die unless there are a lot of holes or a major artery was struck like the aorta.
Being shot in the face actually has a high chance of living if not hit in the brain. Sure there will be high chance of disfigurement and impairment from such shots, but headshots for self defense are not recommended for a reason. Besides the obvious that hitting the head is harder to hit than the chest, but that if you don't hit the brain just right, or puncture the jugular, they aren't going to die all that quick. Too much bone and sensory organs and much of it highly protected. Also, bullets that strike aren't going to cause massive bleeding unless the jugular is struck in the neck which would kill quickly.
The big myth is that bullets are somehow magical and that 1 shot usually kills the target. Too much movie and TV drama crap that makes people believe that. Very rarely do people, or any large animal, dies from a single bullet wound.
Uh....
most large caliber (especially high velocity) rounds to the face invariably tend to find their way to the brain. The brain occupies a large portion of the human skull.
Yes, single bullet wounds to most parts of the body don't necessarily equal instant-death. The heart is a small target, missing it when firing at the chest can lead to either being perfectly fine for a few hours as long as one dresses the wound and takes care of it (hospital) later, or can lead to essentially drowning/suffocating (sucking chest wound, flooded lungs, collapsed lung(s), etc), or a few other things related to interstitial bleeding or infection from busted gut organs if not addressed in time.
But it's actually more likely to die from a single gunshot wound to the head, then it is to live. Especially if aiming at the front of the face and they strike in the face. All the front/lower bones are far more likely to lead to bullet tumbling, which is more often than not what happens with a headshot. It'll bounce around in the skull since the brain hardly slows it down but it's not fast enough to exit through more bone after entry.
You can survive trauma to the brain, like large holes being dug out from various things, but a tumbling bullet is quite likely to strike the medulla. If a bullet so much as glances the medulla, most likely you could be pronounced dead that instant - you'd drop and completely cease to continue any functions. If my anatomy serves me right, striking/severing the medulla not only completely shuts down all autonomic functions, but even if you could be hooked up immediately to all kinds of advanced machinery, it should also render immediate brain death. Striking the medulla is essentially the same thing as decapitating the head. You can do it by severing the medula from the spinal cord, or simply turning the medula into mush itself.
Shots to the lower back of the skull are almost statistically guaranteed to kill on the spot.
Shots to the side, depending on caliber and velocity (thinking above the ears, or near the ears themselves), have an equally strong chance of instant death.
Anything to the top of the skull (as in, boring top-down through the skull from above if they are standing) are nearly guaranteed to kill.
From afar, hitting the top of the skull, almost like grazing, I'd wager is less so, but bullet details are important for that one.
Aiming at the face from the front, if you are hitting the cheeks, brow, mouth area, and have aimed true and center mass (think like an arrow - from your standing posting, their face is squared with you, the bullets unbroken trajectory, if no head present, would travel straight through their head is, out the center of the back of the head) - this is a almost assuredly a much better than 50% chance of producing instant death.
Now, a round that strikes the jaw (as opposed to through the front teeth toward the back of their throat), or far off-center of the face, or to the high cheek bones (fewer open cavities, more bone, different trajectories), regardless of velocity/caliber, such wounds will probably result in 50/50, if not less. Especially if off center (you are squared up with their nose, dead center, but strike an off-angle to the sides of the face, off-angle jawbone strike, etc), it's probably less than 50/50 - but the right caliber and velocity may improve or worsen than.
Any of the above can be dropped by using weak velocity, small caliber rounds.
But even then, and especially with higher-powered rounds, bone fragments can be unpredictable and behave like missiles in the soft brain tissue.
And the chance always exists, even unfavorably with good aim to the better areas of the skull, that the random tumbling just won't work in your favor. A very high powered round may pass clean through the skull with no tumbling, and unless you hit just the right spot on that clean pass, there's a decent chance of surviving that. Sometimes without ill effects, sometimes with devastating changes to your personality, memory, or abilities.
But if you strike with bad aim (not aiming through back of skull) on a fair portion of the bone-dense front parts of the face, the tumbling bullet trajectory may exit before even touching the brain, with it instead destroying a good portion of the jaw and/or cheek bones before becoming lodged, exiting messily through the face, or being too slow to bounce around the skull.
There's even a small chance of so messily destroying the skull, that both the weakened containment vessel and the strong pressure waves just cause the brain to just *plop* on out of the head, quite likely entirely intact. It's actually quite rare, and probably the "best chances" are with .50cal high-velocity rifles more than anything.
Oh, the classical gun held to temple? That may be a true 50/50. Depending on the round, it may pass cleanly from temple to temple and exit without touching anything but the frontal lobes. Said victim may end up with a lobotomy and/or royally fucked up. I don't think there are many, if any, cases where the patient returned to a normal life after surviving a blast to the temple. There are survivors, but generally a shell of who they were.
Hmm, another article I read stated if the bullet crosses hemispheres, you are far less likely to survive. If it only impacts one lobe in one hemisphere, you can likely escape with minimal impacts (might lose a little of the You part, or possibly some left-sided or right-sided ability). And it stated aiming true from front of head to rear of head has the best outcomes, because it may only strike through one hemisphere. But I do believe this isn't specific to BULLET wounds but rather "penetrating head injuries". Bullets are known to tumble and bounce around in the skull; arrows, nails, screwdrivers, knives, all the other accidental and weaponized objects that can be bore into your skull, are not known to move off their straight trajectory. Such straight-through penetrations, unless aiming from up the back of the neck, are highly unlikely to strike the small region that can and does render instant death. You can typically live if it's only a limited portion of the cerebrum that has been bored through, again through with a range of possible side effects.
Of importance: I realized that, when I was nearly finished typing this, I had used "medulla" on many occasions. I don't feel like correcting each area that referenced this, so I'll do it once here:
replace every statement of "medulla" with "brain-stem region." This still includes the medulla, but also includes the brain stem itself, and the cerebellum. Now that I have recalled this, I do believe it would be a bullet striking the brain stem itself, and not the medulla (or it may be the cerebellum) that would render instant death. All three, which sit right near the base of the brain/skull, are crucial for motor functions and autonomic activity.
At the minimum, hitting one of those will render the heart to stop permanently, I don't think any surgery can fix that. Likely at the same time, you become unconscious (due to other effects, not the heart stopping). If that's all that happens, you aren't technically brain dead yet, but your effectively dead because you cut off the brain from both oxygen and sugar, and it can no longer do anything with the lifeless bag of meat and bones attached to it. You wouldn't be able to think or feel or anything, but the brain itself might still be burning up it's last reserves of oxygen and sugar.
Here's an interesting number:
In 2000, Maryland recorded 235 penetrating brain injuries - 208 of them lethal.
How many of those were gunshot wounds, and the actual percentage of headshot survivors, is unknown. Who knows how many assholes went stabby stabby to the head, or how many dumbasses fired a nailgun to their face.
Here's an interesting, presumed fact:
if you put a gun inside the mouth, aiming straight back through the throat out the back of the skull, it should be guaranteed death. If you do it with a shotgun, there shouldn't really be much left of your skull; if you do it with a handgun, even a weak one, it should travel straight to the brain stem/surrounding region of important bits.
[holy shit - why did I type all that? lol]