This movement was produced in grades from 7-jewels in open faced (and possibly hunter) styles, with a standard regulator, to examples such as yours. I don't recall seeing this model with more than 17-jewels such as yours has. Yours has the micrometer regulator. Unfortunately, not much can be said of the case since your pictures don't show a good view of the inner cover quality marks. I don't know if the Omega was produced in railroad grades behind an Omega dial, but basically this same movement in 19 and 23-jewels were produced for railroad use behind Louis Brandt & Freres dials. The 19-jewel, 16-size version was grade CCR, and and CCCR WITH 23-jewels. The 19-jewel version in 18-size, it was the DR. The 18-size, 23-jewel version was DDR. I think I see a semblance of a serial number around the circumference of the crown wheel, but the lighting is such that I am unable to read it. My guess is that the watch would be circa 1910 to 1920. If you tell us what is stamped within the covers, we might be able to comment on the case. Disregard any scratched repair numbers.
I have two of the Brandt CCR versions, one of which I have shown. Basically the same movement, marked so it was approved for railroad use.