Reddit mentions of The Truth About Self Protection

I am not an expert. This is not professional legal, defensive, or other advice. You are responsible for your choices and their consequences.

A few points on home defense firearms

• Any firearm that will keep you safe will also go through a wall, and some firearms that won't keep you safe will go through a wall (including .22). If it will penetrate flesh, it will penetrate drywall. If you are defending your life, you aren't worried about the cost of wall repairs or the engine block of your car outside. Always know your target and what is beyond, and never discharge a firearm at something you are not willing to destroy.
  
  
• To prevent hitting people outside of your home, think about the layout of your home and where/how you will be defending yourself. Ideally, you would have a safe room (the master bedroom, for example) where you can lock the door. Let the home invader have the flatscreen in the living room; hopefully that's all he wants. He'll take it and leave and your homeowner's insurance will cover you (and even if it doesn't, a few hundred bucks is well worth getting him out of there). If he boots open your bedroom door, though, he has now framed himself, cannot move laterally (he's in a doorway) and makes a fantastic target (provided he poses a lethal threat). Have a thick book case or other large, impenetrable object across from your bedroom to stop the rounds that may overpenetrate or miss your target. (And don't count on the bookcase alone; choose a lane of fire that prevents the possibility of injury to innocent bystanders.)
  
  
• The reason we use firearms is that there is an immediate, unavoidable threat of death or great bodily harm to the innocent. In this situation, you need to stop the threat now. Not ten minutes from now. Not in an hour from now. Not in a week form now. Not ten seconds from now. Now. John Mullery continued fighting law enforcement officer Steve Chaney with multiple rounds of 38 special in his chest and one in his head. He didn't stop until a round broke his pelvis and he fell to the floor. Use the most effective firearm that you feel your household can handle. More on that in a moment.
  
  
• The 22 is everything you don't want in a defensive firearm: It's not particularly less lethal than any other caliber (it can pierce major vessels like the aorta and femoral arteries, it can penetrate the skull under the right circumstances, it can pierce the heart, and you may have to shoot your target more times to stop them), but it is less reliable (bullets can more easily slip around the rather armored human skull beneath the skin and exit without interrupting the CNS, people shot through the torso and abdomen may not be stopped immediately). It doesn't help you if your target dies a week from now. In fact, the ideal situation would be, your target survives, but stops his aggression immediately and leaves. Time and again, evidence from the street has shown that in handguns, calibers larger than 9mm or 38 loaded with defensive ammunition (jacketed hollowpoints, for example) are the standard, which is why you generally won't find a department in the US that carries anything less. The one-shot stop rates for such firearms is typically over 90%, meaning higher survival rates for the aggressor (with proper trauma care) and a better chance at escaping injury free for the defender.
  
  
• Your choice of defensive firearm will depend entirely on your needs. If someone tells you a certain defensive firearm is 'the only reasonable option' or 'the best choice' without first assessing your needs and explaining his/her reasoning in detail, consider listening to someone else. If you need to move from room to room, collecting young children from their bedrooms, flipping light switches on and off, and calling the cops, a gun that can be used with one hand (a handgun) would serve you well. If you live alone or with one SO, and you are both likely to be in or retreat to the bedroom in the event of a home invasion, a shotgun or other long arm may make more sense. Remember to choose a firearm that the smallest and least experienced member of your household who is authorized to use guns in defense of life can use safely and reliable. I can discuss this more if needed.
  
  
• As always, observe the principles of gun safety and store your firearms safely.
  
  For more information, feel free to AMAA or check out the following:
  
  The Truth About Self Protection by Ayoob (general home safety as well as limited firearms advice)
  
  The Gun Digest Book of Combat Handgunnery by Ayoob
  
  The Gift of Fear by Gavin de Becker (Provided for some balance. de Becker is generally anti-gun, and much of his advice deals with finding ways to avoid getting to the point of having to defend yourself physically. It's an excellent, excellent book for crime prevention.)
  
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  Happy to dialog or answer questions with anyone who agrees, disagrees, or anything in between. I only ask for mutual civility.