Hey Pcke, what thread were you looking at on the year 17 /26\? I don't remember posting that, and if I did I think it's wrong because I've got zero year 17 /26\s guns in my files. Assuming it is a year 17 /26\, yeah that's a heck of a find as we didn't think they produced them then.
For year 16 factory /26\, I have only a single example & those are rare as hen's teeth, so that might be what you're remembering.
Boris is probably on to something with the factory /136\ looking just like /26\ and often being mistaken for one. They very likely produced guns at this factory in year 17 (there are no examples, but I do have examples of year 16 and year 18, so it's a likely-to-have-been-produced hole).