Recently The Daily Caller presented a pretty good article on three self-defense myths that you still see bandied about. Here they are, with some of my comments.
Myth No. 1: Hit him anywhere with a .45 and it will knock him down.
This myth probably started with the advent of the .45 Colt back in the 1870s, but it has been repeated most often when people refer to the .45 ACP. Nowadays, you will hear it touted regarding the .44 Mag., the .41 Mag., the .40 S&W or whatever new pistol cartridge that has just been introduced.
The truth was discovered way back in 1687, when Sir Isaac Newton published his third law of motion. Newton simply stated that for every action there is an equal and opposite reaction. In other words, if a bullet shot from a handgun was so powerful that it could actually knock a person down, it would also knock the shooter down.
Part of the reason you still see this line of horseshit served up is because you see it in the movies and on television so often. One of the best portrayals of an old Western gunfight is in the excellent Costner/Duvall flick Open Range; it shows a real gun battle, with old guns made with varying tolerances and inconsistent black-powder ammo, with opponents literally just blasting away at each other at short range until hits are scored. But there is a scene that ruins the whole thing; 
Robert Duvall fires his double-barrel 12 gauge through a plank wall at a bad guy, and the blast picks the baddie up and slams him against a wall. Not even a 12-bore at a range of about six feet will do that; not even close. More on that in the next bit:
Myth No. 2: There’s no need to aim a shotgun, just point it in the general direction of the bad guy and fire.
The shotgun is an awesome firearm that is altogether too often overlooked by today’s defensive shooters. However, it is not a magic wand. People who claim you don’t have to aim a shotgun have simply never done patterning tests with their favorite defensive smoothbore.
When shot exits a shotgun barrel, it does so in almost one solid mass. That mass is smaller than a man’s fist. It is only as the shot travels downrange that it begins to spread apart, and it spreads much more gradually than a lot of people expect.
A shotgun can be absolutely devastating at close range; I can attest to this from personal experience, having personally taken a hit to the leg from a 12-gauge at a range of about three feet. (It was just a minor difference of opinion; call it a misunderstanding and leave it at that.) But it’s not a damned paintbrush. A good tight aim is still required.
Myth No. 3: If you have to shoot a bad guy in your front yard, drag him into the house before calling the cops.
As ridiculous as this may sound, it is one of the self-defense myths that just won’t go away. A student brought it up once in a defensive pistol class. There are couple of good reasons why this is a terrible idea.
We live in a time when any halfway-awake forensics weenie can reconstruct your life history from the remains of your gerbil’s three-week-old fart, and people are still spouting this nonsense.
Here are a couple of additions of my own:
Don’t ever fire a warning shot.
Daffy old Uncle Joe Biden’s advice on the topic notwithstanding, this is a bad idea. For one thing, you may well be guilty of negligent discharge of a firearm. But more to the point, if things are bad 
enough that you have produced a firearm to deter a threat, if you are called upon to fire your first shot should be center mass. Shoot to stop the threat; a shot in the air does nothing to that end.
Understand the laws of your jurisdiction.
In Colorado, we are fortunate enough to have what liberals call the “Make My Day” law; state law gives home and business owners the right to use force to defend themselves on their property, without requiring one to retreat. Your state may differ; some places require you to flee before using force, which to my thinking is a horrendous abuse of government authority and a denial of a basic human liberty. But if you don’t want to end up in the crowbar Hilton yourself, know your local laws.
It’s a damned shame that so many folks who write about guns don’t seem to know much about them – including some that should know better.
