I've been fortunate lately and picked up two pre model 15's. Both are very clean. One is 113xxx (1951 I think) and the other is 140xxx, probably a year or two "newer." Both are clearly original finish and numbers matching guns.
The later one has a slightly plum / brown color to the the cylinder. It has not been refinished; is this common? If so, what causes it? Maybe the metal is slightly different and/or heat treating causes the finish to fade to plum / brown over time.
Don't know so fill me in - thanks.
redleg
Photos added:
This one is the "newer" of the two with the plum / brown cylinder. Maybe a harsh cleaning solution or solvent was used to clean it up...?
Here is the "older" one, just for fun and comparison.