you may find some info at the savage arms website.This was the maker of your shotgun,savage/stevens.
Try e-gunparts.com
It's a Stevens 620.
If it is a stock gun it probably has a open cylinder unless someone has added a choke.
Assuming 12ga, $150-$250. sales@countrygunsmith.net
what is the value of a Ithaca 12 ga shotgun
Try e-gunparts.com
Mossberg
Stevens 520A
Turn of the century, inexpensive arm.
100-300
how much is a steven's 12ga model 770 shotgun made by savage arms corp worth?