The scope bases are not screwed on. They were only put on with hot glue. I got the bases a few years ago from traditions when they had them on special and never used them. They are offset and made for sidelock barrels. I wanted to see if they would work on a flint lock so I glued the bases on and put the scope on them. They work pefectly. It' a good thing I don't know how to drill and tap the barrel for the bases or I would have already done it.