Western Field is/was a Mossberg (mostly) 'private label' brand. Remington, Savage, and Marlin made a few Western Field models, but most were Mossberg.
If made before 1968 or so, you won't find a serial number. S/N's were not always used before the great GCA of '68.
Didn't see that specific model number in the Numrich cross-reference guide, though.