Was in Cabela's a few weeks back and saw this in the gun library. It looks like it has almost all of its original finish, except for the backstrap and some scattered areas on the top of the barrel where it may have come into rough contact with some dirt, gravel or sand. The bore appears perfect and the chambers the same. The serial number on barrel matches the butt: 19,xxx. There is no SN on the rear of the cylinder, but it has NOT been "shaved". The SN on the ejector star does match. The chambers do appear to have a very shallow "recess" in each, so it may have been switched to another caliber that way. It also has the expected commercial proof marks added to the barrel (but not the cylinder), as well as a "sold out of service" mark on the left side of the frame. It is wearing much later post-war diamond magna stocks.
The other interesting thing is a nicely engraved (not stamped and clearly professionally done) ownership mark. It says "H. Gordon Raeburn" over "R.E.". I posted about this gun on the S&W Collectors forum when I first saw it and some of the guys seem to have located some great info about Mr. Raeburn. Enlisted in the Royal Engineers in December 1915 and earned the 1915 Europe Service Medal. http://smith-wessonforum.com/s-w-han...ics-added.html
Since bringing it home and checking more carefully, it seems pretty certain that a new .455 cylinder was fitted, then modified for .45 Colt by machining is a very shallow recess to seat the rim just below the back face of the cylinder. Should still take .455 ammo, too.
Thoughts are always welcome.