10AN movement is stamped with a triangle and arrow. Unlike another 10AN movement in my collection with both date stamps, this example has the triangle and stamp NEXTto each other rather than apart. Also, the word "unadjusted" is after the words "seventeen jewels" rather than before it, and the serial number is bottom aligned to the outer edge of the movement. The dial appears to have machining marks emanating from the center of the dial in a radial pattern which is easier to see as the light reflects off the dial.
I'm stepping out on a limb here Nick, I hink this is a 1927 Lone Eagle 5000. I could be wrong but here's my thinking.
* 1926 s/n 6560349 is at the beginning of the known 5000 case s/n
* 17 Jewel 10 AN with s/n 255304 will also be at the start of the known run of 5000 movments
* Additional down arrow mark on movement in known only to exist on 1927 Lone Eagle
* hands seem correct (but dial should have open nine)
1927 Bulova Lone Eagle is my ID - one of the 5000 to boot!
See my comments here: https://www.mybulova.com/watches/1926-unknown-10870
Again an interesting mix of correct parts, but what we typically see in either the pre or post versions.
Again based on the movement I put it as part of the 5000 range of Lone Eagles, but still a 1927 Bulova Lone Eagle