I can answer your first question with some caveats. As best I can estimate is at least close to the following data. The standard statement that there were overlaps in date and serial numbers due to old stock and new. Dating a specific model is tracked by ship date and not manufacture date plus S&W did not ship in serial number order.
- 1899 & 1902 – 2 line caliber ending near the frame left side
- 1902, 1st Change – 2 line caliber centered over knob starting at 73,251 (1906) left side
- 1905 – 2 line caliber centered over knob up to around 120,000 (1909) left side
- 1905 – 1 line caliber centered over knob started at 120,000 left side
- 1905 – 1 line SMITH & WESSON centered over knob starting at 270,000 (1917) left side - caliber on the right
- 1905 – 1 line SMITH & WESON centered over rear of lug up to 400,000 (1922) left side - caliber on the right
As far as cylinder rotation, I assume we are talking about top-break revolvers from before hand-ejectors. As far as I know, all top-break revolvers had their sideplates on the left side except the 38 Perfected, and that was the side that the hand was installed, barrels turned to the right. All hand-ejectors had their sideplates on the right, and the hand was on the right side as well so the cylinder turned to the left. I believe that is still the case, but I do not collect any model named revolvers.
