As already stated…check the laws in your state.
Arizona provides no use of deadly force to protect property, but has castle doctrine and no duty to retreat.
You may NOT be sued by the perp or their family in a justifiable self defense shooting.
You may shoot someone who is definitely raping a woman (or man I suppose) molesting a child, or kidnapping someone.
You may shoot someone if you are in fear of grave bodily injury or death…disparity of force also comes into play here (multiple attackers, a very large person attacking someone very small, young/strong vs aged or handicapped) any type of weapon is something that can cause grave bodily injury or death (knife, screwdriver, baseball bat, brass knuckles, bag of quarters, boot to the head etc.)
My personal gauge is this: if I figure I or my loved ones may end up crippled, raped or dead, I am going to make damn sure I stop that from happening.
I want to go into the courtroom knowing in my heart that I am 100% justified for using deadly force. That way I can live knowing that what I did was right according to the circumstances at that moment in time…whether that means I spend the rest of my life in jail or as a free man doesn’t even matter if you KNOW what you did was right in YOUR mind.
If you have any doubts in your mind about pulling the trigger at that moment, then you probably shouldn’t.
Learn the law and let good morals guide your actions and you can handle any outcome.
My two cents.