Montgomery Ward and company made my Western Field model sb-100b.
sb 60a
Stevens.
i have a wards western field m #30 - sbv5662a
Savage 187N
$450
10- 100 USD or so
Stevens made the sb-300. You can cross reference it and it comes out to a Stevens 311
$50 in good condition
12 gauge double barrel shotgun
Your Western Field model SB-312 double barrel shotgun was made for Montgomery Wards(western field) by the savage arms company.The Savage model 540D shotgun is the same shotgun as yours.If you go to the savage web site they may have more info on this model?
I have one that was new approx. 1969.