If you have an SB-1/shotgun frame, you can change your shotgun barrel for any shotgun barrel except a 10Ga barrel. You can also add pistol cartridge calibers and the BP 50Cal Huntsman barrel onto your frame.
You can verify what type of frame you have by taking off the stock. If you have a solid piece under the stock (just a screw bolt hole) then you have a shotgun/SB1 frame. If you have a skeletonized frame under the stock, it is a rifle/SB2 frame, this type of frame will allow you to use high pressure rifle barrels in addition to the shotgun barrels.
For additional info and pictures, go to the FAQs. Hope this helps.