I believe it to me a 1938 montgomery but it has the shield symbol on the movement that resembles the date code for 1928. My pride and joy by the way
The shield date code is for 1929 and 1939. So it is in line with the case serial # being 1939 as well. I am not sure if it matches the Montgomery case. Check out this one in the DB, note the recessed crown and it appears more narrow. www.mybulova.com/watches/1938-montgomery-9765
The closest model I can find to this is a 1940 Lone Eagle
Nice watch, here is another possibility "Engineer".
An Engineer ad is referenced in posting below. I am for some reason unable to insert images in comments.
In reply to Nice watch, here is another by neetstuf-4-u
I believe that crystal specs may play a part in the ID of this watch, as the models mentioned are all very similar in appearance but vary in size.
I would say that it's a 1939 Bulova Lone Eagle "A"