What year was the western field 12 gauge model emn 175?

It is very possible that your Western Field model EMN 175 was made by Marlin.The models EMN 171,and EMN 176 were made by Marlin for Montgomery Wards.The model 50 marlin is the model 171 and was made from 1925-1930,and the model 176 was the marlin model 55.