For 55 years I've been an active shooter and regret to say that I've witnessed
very many examples of careless gun handling--some of which resulted in negligent discharges. I'm guilty of one which blew a hole in my new truck's door.
If, in a recreational setting in the field, on the range, or at home, and we're looking at each other's guns, my rule is to have the actions open if it ain't cased or holstered. I've observed that some folks don't like to be directed in this manner and resist this etiquette. These guys I avoid.