The 10AB is from the FHF 324 ebauche, as is the 10AE, 10AM, 10AN, 10AR, 10AW, 10AX, and the centre sweep versions. Some of these exist in all jewel versions, like the 10AE and 10AN in 7, 15, 17, and 21. There were all USA made versions like the 10AX as well.
It is very likely that the 10AB was made with higher jewel counts also, because all of them had more than one configuration/jewel count, although I can't confirm this.
I have a 7 jewel 10aB with a 1934 date code.
So I'm updating the movement record to show both 17 jewel examples as currently listed in root record, and to include 7 jewel examples as per photo posted below by Admin (and Mac's comments).
Do you guys think the 17 jewel entry could be a typo? I searched for both 7 and 17 jewel examples in the database, and found no occurances using both "10AB" and "10 AB" search terms. I know the 7 jewel movement exists :)
I have a Bulova 10AB date 1934. It is seven jewels like the one pictured above.