Thanks for posting the numbers on the Series 0, Kent. I understand that the watch may not be "uncommon" or "scarce", as per Shugart/Engles and Gilbert. Perhaps they need another star rating for "relatively uncommon". ;-)
I had mentioned that my scarcity feeling was based on how it seemed to me (Personal observations implied, methinks.) rather than consulting factory records, etc. So I feel compelled to add that a look through the posted images of Series 0's on pocketwatchdatabase.com (As a sanity check.), I see a ratio of 2 HC configurations against 27 OF, FWIW. The factory numbers you,
Kent , are showing, amount to ~82% of total production. So ~7 out of 8 made were OF. The statistics from the observation of the 29 examples of Series 0's on the database, end up closer to being 93% OF, or better than 9 of 10. If the actual production records matched the observations on PWDb images, which would be highly unlikely, there would only be 875 HC movements to 11,625 OF, making it at least Shugart "sparce". Granted, there are many other variables related to who posts what and where, but it sort of bears out my personal observations, i.e., I'm not as crazy as I look.

I'm not claiming that the factory numbers aren't correct, only that it seems, via personal experience, that there is a larger differential between the HC and OF than is indicated. Perhaps people with HC movements don't sell them as often, or are less likely to post images of them. We'll never know.
I'm OK if anyone wants to point out math errors, etc. I never took a statistics class, so I just derived numbers from basic math.
Out of morbid curiosity, what do you,
Kent , show on production number for the 12s HC/OF Keystone Howards. Thanks again. Cheers.