No idea Tinker, I found out they are in a few movies (like 3:10 to Yuma (2007)).

Was thinking - these wouldn't be any more likely than any other cap and ball revolver to chain fire? How often do you hear about that happening to western shooters (or how often does it happen?) I guess it's just that your hand is in front of the cylinder so in the event it does happen it's probably going to be much worse.