Have you posted this gun anywhere? I'd love to see it. I have a Colt Bisley model that was extensively modified by Colt (I have the receipt for all the mods), and I would love to see another possible example of their service department work. Particularly to see if there are any little ampersands stamped on there.
Also, since you broached the subject, the main thing about the Triple Lock which is the focus of this thread that makes me suspect that the S&W service department wasn't the one that did the modification is the blued hammer/trigger. One thing that SWHF has taught me is never say never when it comes to the service department.
Any chance this gun has a star, diamonds, or dates on it? With guns this old it's entirely probable that multiple people have repaired and modified it over the years, and its well worth checking to see if some of those people worked at the service department.