Jim,
Nice watch and thanks for the pics.
I haven't kept close track of the serial numbers for these 17 jewel dome model Rockfords, but my recollection is that they are widely scattered and not restricted to specific runs. I don't have any production estimates for them, but they show up with enough frequency that I wouldn't call them rare.
Around 1895 or so (and later), at a time when the Co. was in receivership, quite a number of mvts were upjeweled at the factory from 15 or 16 to 17 jewels (the period reference for this statement isn't close at hand...some 18s mvts were upjeweled to 21 jewels). I wonder if Rockford (or the receiver) knew what "grade" these were. Maybe they did assign a specific grade number for them, but since the Co./receiver was probably interested only in raising cash at the time, it may not have made any difference to them to do so.
Some of these mvts fall into grade runs shown in Rockfords serial number list, but a run of numbers doesn't necessarily translate into a bunch of mvts finished identically as a given grade. Cash was important, not grade number consistency.
All FWIW,
Greg