Is there nothing in a non-converted Ruger 3 screw that prevents the hammer from striking a round in the chamber if the hammer is pushed? Back in the day were unintentional discharges common?
I don't know about the old Ruger's. Hickock45 does a nice video on the Colt style sixguns, they should never be carried hammer down on a hot one, it didn't take much of a bump to ruin your day!