I appreciate the question, and will attempt to stay on-topic. As I read here, I see things I agree and disagree with. Here are my opinions: I will use a firearm when I believe deadly force is needed to stop a threat to me, my family or another that I care about. I won't go into what constitutes various threats, as these can be many different things in the different jurisdictions in which we live, other than to say, for me, it would be a matter of imminent serious bodily injury or death to me or another. I shoot to stop a threat. Stopping a threat usually requires shutting down the Central Nervous System, CNS for short. My shooting targets are the CNS, or center mass of the target to acquire CNS targets. I continue to shoot until the target no longer presents a threat. Respectfully offered, there is no thought of 'mercy killings' in my repertoire. I protect myself by knowing federal, state and local laws that outline use of deadly force, and by applying deadly force only as neccessary. Absolutely neccessary. Then I have an attorney to handle any legal matters for me after a shooting, which follows many of these types of events. Like many aspects of my martial arts, it's best for me to know my limitations, practice likely scenarios, prepare myself mentally, and guard against having to employ this tool. But when the situation dictates, employ it with extreme prejudice.