Thanks for the reply, but the serial numbers on the butt, barrel & cylinder are all the same. Item# 858787226 on gunbroker has the same notch under the barrel.Unless my eyes are playing tricks, someone has really bubbaed up the first one. Is that really a notch cut out of the barrel to accept the knurled ejector rod knob?
I think the frame may be a 4th change, but the barrel, cylinder and ejector rod are newer. The finish on the barrel and cylinder don't match the frame. There is no way the real 1905 4th change had that notch carved in it.
The serial puts it between 1915 and 1942. Given the placement in the range, and the various dates, I'd hazard 1920's.