The Reality:
Criminal attacks usually happen very quickly and are often brutally unexpected. Under the stress of an attack, your body will go into fight-or-flight mode and will dump a massive amount of adrenalin into your bloodstream. This is good, because adrenalin will give you the physical strength and stamina to run away (if you are able to escape) or to fight back fiercely (if you cannot run away). But the adrenalin rush will also cause your hands and entire body to shake, your vision to tunnel in on the threat, and your brain to nearly stop registering input from your ears. These are all very predictable physical responses to being attacked.
Criminals aren't like cardboard targets at the range: they don't stand still, they don't move in predictable patterns, and they don't play fair. They move quickly and erratically and do unexpected things.
What this means is that getting a good, solid hit under stress may not be as easy as it sounds. Nationwide, law enforcement officers who get involved in shootings have a hit ratio of only around 20%. That means that 80% of their bullets do not hit the attackers! There are a lot of reasons for this, but
the important thing to remember here is that you will need every advantage you can get. For the best chance of hitting the attacker at all, you will want to aim for the very middle of the largest part of the attacker's body that you can see.
The Reality:
Even if you do hit the attacker in the arm or leg, marginal hits are much less likely to stop the attack quickly enough to save your life.
If the attacker is drunk or hopped up on drugs, he may not even notice he's been shot until blood loss shuts his body down, which can often take five minutes or more. A lot of very bad, and very permanent, things can happen during those five minutes.
Defending yourself with a handgun isn't like the movies. Your attacker won't be blown backwards when he is hit. He may not realize he's been shot even if the hit is a solid one.
Even if he takes a bullet right through his heart, it may take 30 seconds or more for his brain and body to stop working. Thirty seconds may not sound like much, but it is enough time for him to shoot an entire magazine of ammuntion at you, enough time for him to fatally stab you, enough time for him to club you into brain-damaged unconsciousness.
The truth is, if you are attacked by a determined criminal, you will very likely need every advantage you can get. For your best chance of survival, you should aim at the largest part of his body you can see and you should keep fighting until you know that the attacker is no longer a threat.
The Reality:
If your attacker does not die (80% of people shot with a handgun survive), then he will very likely be charged with attacking you.
The Reality:
Maybe, maybe not. Some criminals do amazingly brazen and determined things under the influence of alcohol, drugs, or stupidity.
While most defensive uses of a firearm do not involve any shots being fired, you cannot assume that your criminal will be smart enough to run away.
It's also important to understand that criminals do not fear guns. They often own guns themselves, and spend their lives handling weapons of all sorts. The mere sight of a gun is not going to cause the criminal to faint! Some criminals will run away when the intended victim brings the gun out. But it is not the gun itself that makes them run away. A criminal runs when he believes the victim will shoot and kill him if he continues his attack. If the intended victim does not have visible resolve that she will use the gun if she must, the criminal may very well continue his attack even though he has seen the gun.
