I have a blue 5 screw, 2nd model, 5 shot, 5 inch barrel top break revolver, serial # 49204. It has a dual action mechanism for exposing the cylinder. The rear sight has to be pulled rearward, while, simultaneously, pushing the side latch forward ( like on a swing out cylinder). Bore and cylinders are crisp and clean , tight mechanism, and, appears to have been re-blued (guessing, due to age), by the factory, or an equivalent job. I have Pythons, so I know what quality bluing looks like. I'm curious as to when this was manufactured and when the dual cylinder opening mechanism appeared. Also, the hammer and trigger seem to be casehardened.
Thanks for any help here.