1960 (M0) 17 Jewel
From the Aurore-Villeret 120 ebauche. Bulova usually modified the balances at least, and the parts from the original ebauche are not always interchangeable. Dates back to the 40's, and precedes the 6AH and FHF 120.
The 6BM is based on the 6BMC, which in turn is based on the 6BO, which is from the 6BL, which is from the 6BA.
It looks like we do have it in the movement database... http://www.mybulova.com/search_bulova_movements
Early 60's production.
Anyone heard of this model before?