Looks like a Model 70 to me.
Mossberg made guns for Mongomery Ward and they were sold under their house brand Western Field. Serial numbers weren't required by law until the Gun Control Act of '68, so it's no surprise that there are none. The model 70 was made 1933-34, then replaced in 1935 by the Modlel 73 which had steel swivels added to the stock. If you've got no swivels, you've got a model 70.
Great lookin shooter by the way...