I'm no great hand gunner, but for suppressing fire, like you said, and maybe a lucky hit or two at distance, I can do that. The police officers on my shift are friends of mine and I would not leave them hanging if their lives were in danger and I could help. Nor would I shirk my duty if I felt that I could stop a shooter. I could not look in the mirror if I did, and could not look at my son. I'm far from a hero, but I will stand my ground and fight if need be.
American citizens have duty too. Or at least we were always supposed to have duty to our communities and country. That's how we got here. I still believe in it. Along with personal safety and defense of my family, that's why I carry. "For God and country!"
"In all things do your duty" - Robert E. Lee
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This pretty much sums it up here!
Well said @MRH
Protection for my Family, friends, myself and any other who cannot do so themselves.