Don't relish the thought. I hope I never have to use my firearm or any weapon to take the life of another human. Having said that if put in the position to have to take the life of someone in my on defence, family member or innocent third party then at that point I will do what I have to with out regret.
not really trained but with no regrets, i've been i the situation where i could of killed or been killed, thankfully it didn't go that far, but if its my life and that of my family's, no regrets. period.