I was going to offer the same comment that Lee did. Its possible that it was
a special order, but, of course, only a factory letter could confirm that. That
would have been a big deal, at that time, so that is very doubtful.
The sales of K-frames was not slow, in the 1920's. This is about a 1922 gun;
s/n in the very early 600,000 are about 1930. This is about 200,000 guns in 8 years
or so, which is 20,000 to 25,000 guns per year. That is the average production
over the entire 40 period , from 1900 to 1940, so its very unlikely that this
was a late-shipped gun.
I would say that the original barrel has been replaced - at some point - with
this 2" barrel. The factory may have done it, and they may have serial-numbered
it to the gun.
The easiest thing to do is to post this on the S&WCA site, and maybe Roy can
give some indication as to how the gun was shipped.
Later, Mike Priwer