There are a substantial number of gun store employees who go off folklore and BS. They are no more qualified on legal and tactical issues than I am on judging a dance competition.
As part of your responsibilities that come with owning a firearm with the potential for serious use, you need to know some things about the use of it.
1) KNOW THE LAW in your jurisdiction. Most use of force laws are similar, but you MUST know what your state's laws provide. Most if not all states have their statutes on line and you can find them with any search engine. If you are really lucky, you can find annotated versions (they have case law with the statutes, showing how they have been interpreted). If you have a law school nearby, you an check the books themselves and read the annotations. Without doing such research, you simply cannot even ask informed questions, let alone know the answers.
2) Go read this string here:
CHL holder trying to break up a fight loses pistol, is killed by police. There is at least one book (the one by Patrick and Hall) that I recommend, which although directed at LE, has very good information about self-defense generally, ballistics, threat recognition, and the like. You MUST know these things before you make a decision about using force, so you can articulate from a position of knowledge why you did what you did. What you learn AFTER the shooting is not relevant. You should also search for and read the cases I cite. I do this stuff for real as a prosecutor, author, and teacher.
3) There are a few strings on home defense in which I have laid out some pretty decent advice on layers of deterrence. The more difficult it is to enter your home unlawfully, the less likely someone will try. That also contributes to the reasonableness of your belief that force is needed. At my house, I have floodlights over the side facing the street, "no trepassing" signs, so it is not even lawful to enter the property, a 6 foot padlocked chain link fence, and my doors are never unlocked except to go through them (and if yours are ever unlocked for longer than that, slap yourself and fix your complacent mindset). We also have medium sized protective dogs (a rott and a rott X, both in the 80-90 pound range). If someone tries to get in despite the response of the dogs and after going through the other layers, they are really a bad actor, and once the door frame breaks, there is no other conclusion to draw.
4) Know your local culture with regard to private citizen and LE use of force. Where I live, the culture will give a collective shrug and it will be over. I expect that to change in this state, sadly, and plan to move upon retirement. If you live someplace dumb, err, less supportive (CA, NJ, MD, MA, other occupied territories), the response might be different.
5) Special note: I don't have kids, and we almost never have anyone in the house. I can do some things that others can't. If you have kids, the proper means of storing a firearm is
ON YOUR PERSON. Loaded, ready to use, in a qualify holster, with a quality belt, on you. Not in a closet, on a shelf, in a safe, or some other brain dead paradigm.
