Bulova cal. 10AN 21 jewel movement
I am very familiar with the Bulova cal. 10AN movement in its 15 and 17 jewel configurations, as I own and have serviced several Bulova models with this movement. But I recently purchased a Bulova in an Anchor step-sided gold-filled case with a 21 jewel cal. 10AN movement. The cap stones are friction fit, not screwed down, and the movement is marked "6 adjustments", which would lead me to believe this is an unusually high quality of finish for the cal. 10AN.