J. Stevens Arms and Tool Company made guns back in the first part of the 20th Century. Savage bought them out in 1936. Savage continued to make guns under the Stevens name, and I think they still make a couple.
You got several different types of shotguns. Singleshots, double barrels (both over/under and side by side), pumps, automatics and bolt actions. You haven't said which type you have, and they all would have different values. I'm guessing, though, that you have a single-shot breakopen. Something like this.
The "full" marked on the barrel is the choke. They are talking about choke tubes, in this article, and your gun has a fixed choke, but choke is choke. It will tell you what it is.
The single-shot, break-open, full choke shotgun is the most common, and least valuable, shotgun out there. You can get one, new, for right around a hundred dollars. Used ones show up in the want ads, all the time, for 75 or so. It has no collector value - there's just too many of them around. It's just a good, inexpensive, all-around shotgun. Like something the farmer would keep in the barn, or behind the kitchen door.
Meddle not in the affairs of dragons, for thou art crunchy, and taste good with catsup - George of Lod, Year of Our Lord 297
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