If you find out it's on a newer SB2 frame (FAQ's) and you don't want to shim the barrel, you can always sell the barrel on the classifieds and then send in the frame to the factory, and have a new barrel or barrels fitted.
If it turns out you have an SB1 shotgun frame, then you can part out the gun, barrel, receiver, and stock set, and sell on the classifieds on this the H&R forum, and recoupe maybe all or at least most of what you've invested, or even work out a trade to get the rifle to work for you.
I started out with a single rifle, and through the classifieds, buying, swapping, and selling parts, I've assembled five rifles to which none are original rifles.
Nice thing about coming here is you have plenty of people who are willing to help.
These are great little guns, and what now seems to you like you got taken, may just end up being your new addiction once you see how easy they are to tinker with and get great results.
Happy New Year!