External/manual safeties have zero to do with preventing an AD, it is safe and proper handling that makes the difference.
While I do agree with you on your brain is the ultimate safety I disagree with you on safeties. External safeties are safer. I have a 40 cal hole in the dash of my truck to remind me of that.
Mjbskwim, No, I don't have any double action revolvers. Only single actions. But I see your point.