It's all about the individuals fear level, if you are in fear of losing your life or the lives of you family and or an innocent victim/friend. From the actions of another.who has the will and intent, and means to take your lives, You have the right to defend those lives. I don't think that a reasonable man can argue that you were neglegent if such a situation occured. You can't muddle around with this, or you will second guess youself into an early grave,
Your actions must be deliberate and steadfast, once you start thinking things like what if this or that happens, you are dead or you got lucky. When I took my carry test in NY in the early 70's, the Officer who was giving the verbal interview, "that's the way it was done back then", also asked me if I minded that he was training a new officer, and if it was ok that he sat in. I said of course not, "what else can you say", he then introduced the officer we shook hands and he sat down with us, he then told the officer that he was going to ask me, a few questions. I had that feeling, you know the one you get when you know that you better get this right, or your out of the parade. So he did it, he asked me Sir do you know when you are allowed to use "deadly force", I thought and said to myself don't over think this, So I asked if he wanted me to give an example, and he said that would be fine. So I said, , if I am walking down the street, and a man pulls a gun and points it at me, I can pull my gun, and shoot to kill. He turned to the other officer and said, you see, Mr xxx. knows the use of deadlly force. That's the kind of answer we want to hear. He also told me that there were only 2 times that a permit holder was allowed to shoot to kill without warning, "I don't know if these are still the case, so please don't take this as gospel", but they were, If you see someone committing 'arson', or 'forced sodomy'. I could never figure out how one could be sure of the second one, but figured I probablly would never have to concern myself with that one. He said that I would be hearing something back in 30 days, a day and a half later, my permit was granted. I carried in NY from 1974 to 1996, when I sold my business, and left for sunny Florida. It saved my life on 3 occasions.