Six Shot Safety has been sought in the past.
Percussion Colts typically had a notch in the hammer nose and little pins set between chambers. An old Colt with much use will have the pins battered down beyond usefulness.
Some of the Manhattan revolvers had extra bolt notches to hold the cylinder between chambers which must be more secure.
Remington percussion revolvers (and the Ruger Old Army) had substantial notches between chambers. The hammer nose down in one of those is not likely to go anywhere.
The system did not carry over much to the cartridge era. I have not looked close at a Colt House or cloverleaf to see what they do.
The NAA MiniRevolvers have notches like a c&b Remington which engage their blade type rimfire firing pins.
Some say it is ok to carry a SA with the hammer down between chambers and the firing pin trapped between case rims. But it doesn't take much of a nudge to let it shift.
Freedom Arms '83 has a hammer block but they still have a 4 shooter warning on every page of their manual. They trust you with the '97 loaded under a transfer bar... a little.