Sorry- not all guns are marked. Some may have markings concealed when the gun is closed- you need to remove the barrels and check underside of the barrel and the receiver. If you do not know how to do this, stop and take it to a gunsmith.
Try the original maker and e-gunparts.com
Need the maker of the shotgun
Try e-gunparts.com
you may find some info at the savage arms website.This was the maker of your shotgun,savage/stevens.
Find a gunsmith and ask for help. Follow owner's manual instructions. Contact the maker if you don't have a manual.
Find out who the maker of the gun is and see if they can help you with the model name and number. If this is an old gun and the maker is no longer in business check with a professional appraiser. The number by itself does not mean much.
You will have to find a listing of all the serial numbers from the maker for the shotguns they made and go through them.
Find a book published on the company that made it and look for sn data. Try maker websites. Many have sn data on them.
On the breach under the barel
If that "small figure of a man?" is a knight in armor, you probably have a Bayard manufactured by Henri Pieper or Anciens Etablissments Pieper in Belgium.
Go to Numrich Gun Parts Corp.It will be helpful if you know the original maker of your shotgun,as all guns that were made under the Western Field name(Montgomery Wards) were made by outside firms for Montgomery Wards.If you list the model number of your western Field shotgun,this can be cross referenced to the original maker and help you get the right model of shotgun to locate parts.
Your question cannot be answered without you providing the name of the maker of your shotgun,and then we can determine if there is any public data to identify the year of manufacture.