By no means am I a world-class expert on this topic, but I am a lawyer. I do a mix of white collar crime and complex commercial litigation now, but I’ve clerked for judges at various levels and seen a number of cases of claimed self defense. I even drafted the opinions / rulings for the judges in some of those cases.
A significant amount of what is posted here, in my opinion, overestimates one’s right to self defense. Even castle doctrine is not quite a license to shoot anyone who enters your house without your permission. Depending on your state’s specific rule, castle doctrine may mean, e.g., no duty to retreat and a rebuttable presumption that you were acting in self defense.
A point that is rarely discussed by CCW enthusiasts is the reasonableness of the force itself. Shooting to kill is the most extreme force that we have available to us. Based on what I’ve seen, shooting in self defense is generally deemed legally permissible when a stranger has forcibly entered your home for the purpose of committing a crime. That tends to be the legal outcome regardless of whether your state has adopted “castle doctrine” as a statutory rule.
Outside your house, especially if you’re a physically capable man, I would not recommend carrying a gun without also carrying pepper spray. If you shoot someone to preempt a fight, end a fight, or avoid losing a fight, when a less-lethal option would have given you the time and space needed to carry on with your life… you might be fine, but you’re on very dangerous ground. Even in a state with stand your ground, (a) that’s just a rebuttable presumption that can be overcome by the facts of your specific case, and (b) force ALWAYS needs to be reasonable. Even when some level of force in self defense is legally justified, a prosecutor may decide you didn’t use a reasonable / proportional level of force.
In a criminal trial, the judge gives the jury instructions on what the law is, then asks the jury to apply the law to the facts. From there, it’s hard to say what the jury actually does. The jurors may or may not understand the instructions they were given. The simplest heuristic is for them to apply their own personal standards of what is reasonable.
Another problem is the availability of evidence. In the absence of video footage or neutral witnesses, the prosecutor can repeatedly tell the jury that they only heard one side of the story because, sadly, so-and-so is no longer here to tell his version of the events, due to being shot to death by the defendant. If you fired multiple shots, the prosecutor will harp on that as well.
All that said, I still carry everyday. I also carry pepper spray. My mindset is I have it if I need it, but will do whatever I can (besides give up my life or my family’s life) to avoid using it.