First, a big THANK YOU to Ralph for your kind words!
Second, in trying to address the comments of the original post in this thread, I note that "Standard Catalog" and "Smith & Wesson 1857 to 1945" make use of the notion of engineering changes, that were developed in the service department for making repairs. These collector-nomenclature concepts were never used in the factory catalogs, flyers, All-Model Circulars, etc, whose primary purpose was for selling guns.
It turns out that the factory advertising documents do not have the problems that collectors experience with the nomenclature being used. Specifically, factory letters describe early 4-screw square-butt revolvers as a model of 1902, and a 5-screw round-butt revolvers as a model of 1905, when in fact, square-butt models are always a model of 1905, and round-butt models are always a model of 1902.
Another problem with the collector nomenclature is that is violates the factory distinction between 1902's and 1905's. The following image is pages 38 & 39 of the 1912 catalog.
The first line of the last paragraph clearly states that 1902's and 1905's are identical except for the butt configuration. This statement, using the factory nomenclature, is always true, for contemporary models. The collector nomenclature denies the existence of a model of 1902 in about 1905, which voids the factory distinction, when in fact, the two models were always produced side by side (except for a period during WW2).
This confusion about two models vs one model did not have to happen. Instead of denying the existence of the round-butt model, it should have continued to exist. For example, the addition of the 5th frame screw in a round butt frame would simply be a 1902 2nd change. To maintain the factory distinction, the square butt model with the 5th frame screw should be a 1905 2nd change.
This implies that, at its introduction, collector nomenclature should have called it a 1905 1st change, which makes it compatible with the factory rule that, except for butt configuration, contemporary models are identical - which means that they have the same name structure.
This would clear up some of the confusion caused by the collector nomenclature. It may not address all the problems, but it does address one of them.
Regards, Mike Priwer