In reply to Possibly, but these movts by Reverend Rob
Thanks Rob. Second example below has the latter Bulova Watch Co. signature (but a lower serial number- go figure). First example has the earlier Bulova W. Co. signature. By 1924 we see the asterisk date symbol, so perhaps 1923 for second example and 1922 for first example? We don't know the "date" the movement signatures changed, or if there even was a "firm date" for change. Their may have been an overlap of date of signatures.
The hallmark theory is all We have at this time for non Cased Movements not bearing Bulovas' published method for Date of production: http://www.mybulova.com/sites/default/files/image/Bulova-Year-Marking.g…
Movements hallmarked 'Bulova W. Co.' Date to 1922 and prior.
Movements hallmarked 'Bulova Watch Co.' Date to 1923.
In 1924 the published method initiates and all Bulova Movements bear the 'Bulova Watch Co.' hallmark .
In reply to Here is a 17 jewel 6PPI 1922, by offrdmania