IMO the "bolted safety" is a rudiment from older days; "The Big White Hunter" used to have a personal gun carrier, normaly a local native guy who was, more or less devoted but who has no idea how the rifle works. He just carried it. When the hunter and carrier were in the "bush", hunter normaly carried his lighter bolt action rifle and the carrier took care of the heavy double. In many situations the double was loaded for using as a back up gun. That愀 why the "bolted safety" has been added to some big doubles.