This one is for me quite fascinating; another "what the heck is that?" purchase. Based on the raised gold numbered dial, it would seem to be a Bulova Regulator, but the indices and seconds track don't match. Second hand appears to be the same as a Regulator, but is longer. Hour and minute hands match as well. There are 2 Regulators currently in the database; the one with a 1942 case date has a s/n variance from this one of 358.
The dial has a notch at the bottom that indicates it was refinished. The outer seconds track doesn't quite match the perimeter of the numbers on dial, which leaves a little more space between the track and crystal opening at the top. I'm thinking the refinisher used what they had on hand as "close enough".The spacing between dial numbers and crystal opening is equal all the way around. There is a little "play" in the movement at stem when in the case which allows a tiny bit of movement, allowing face to "shift" when case isn't snapped shut. After fussing with it for a bit, I got the face to line up perfectly, with the exception of the spacing at top due to uneven application of seconds track.
Case back is stainless and only has a s/n on exterior. Inside has standard Bulova New York markings that are really light and hard to photograph. Lots of service marks. Bezel is extremely clean with only tiny dots of wear on front corner high points under magnification.
The most curious feature is the movement. I considered the possibility this might be a "Medical Officer" with a swapped dial, but they appear to have used a 10AX movement, were lumed and had lumed hands, as did military issue with hack movements.
Subject watch is a 1943 dated 16 Jewel marked 10AK. Some Bulova Military watches of this era had this modified 10AK movement marked as such and are referred to as 10AKCSH (Center Second Hack). This watch doesn't hack...is this an internal issue or is this a non-hacking "10AKCS"? Has anyone ever identified a non-hacking center second 10AK?
Could this be a prototype or distinct unknown third model in this case with a refinished dial? Is it a reworked Regulator? I have no idea. I do know I like it and it keeps nearly perfect time.