To the OP, since it appears a handgun is involved in the mix,
thisis a good site with up to date info. Do not confuse it with legal advice. You can search individual state's attorney general sites for specific legal statute. Don't be wrong, even out of ignorance, 'cause it can earn you a trip to the graybar hotel. It's a sad state of affairs when it's this complicated to take personal security into your responsibilty. Like tax code, it's all gray by design.
Also, if you have no training, you are a timebomb waiting to go off. Get some, and push away the curtain of ignorance. The three legged stool of AOJ must be met for legal justification of use of deadly force in defense of self and other's under the mantle of your protection, in most every state in the union. If you don't understand that, you don't know enough. Not a dig, just an illustration. Massad Ayoob at MAG40 is a good place to start. Get trained, know the law, and stay safe. No one ever filed papers because they got out of harm's way.