it depends
First off on the condition, second on the model, barrel length and then restriction. The Stevens guns were very nice American made doubles and pumps of incredible strength, average handling characteristics and affordable.
Is it a Model 311?
Does it have 26 or 28 inch barrels?
Is it in good, fair or excellent condition?
I would say anwhere from $200 to $400 dependent upon condition etc.
I personally would like to see a picture, being a big 16g fan.
Since your great grandad gave it to you, I assume you intened on cherishing it, shooting it and caring for it so that you might be able to pass it in to your children.
