Contact Numrich Gun Parts. They have a rather detailed web site and they are also the world's largest supplier of parts for older guns. You will also find a downloadable parts list and exploded view of that model.
Answer
This and just about any other part for a model 311 can be purchased from Numrich gunparts corp ,their web address is www.e-GunParts.com hope this helps
We maintain a good inventory of parts for the Stevens 311, including replacement wood. sales@countrygunsmith.net
Yellow pages category = GUNSMITHS.
The Stevens 311 is a double barrel shotgun.
there is the Stevens side by side shotgun model 311
The best that I can do is state that the Stevens model 311 side by side was discontinued in the year 1989.
www.e-gunparts.com
The original Savage?Stevens model 311 shotguns were made from 1926-1945.The more recent made Stevens model 311 shotguns were discontinued in the year 1989.
You might find one at Numrich Gunparts
Numrich Arms has parts for the 311
Stevens made jc Higgins shotguns ,the model 311 interchanges with the jc Higgins
Find a gunsmith to show you. Go to the library and look for firearms books on maintenance.
Not recommended.