ORIGINAL: Bandhunter
The frames are not registered at all. In fact you can purchased them seperately without a pistol, rifle or muzzleloader barrel. All encores are interchangeable as far as barrels and stocks are concerned. As mentioned before, it is illegal to use a rifle buttstock and a barrel less than 18" in length on the same frame. It is printed on the end of all rifle buttstocks. The Prohunter is just a newer version of the encore.
The reason I asked is I see there are a few more options in barrel selection for the pro hunter. One more off topic question, do you think a 28" barrel wouldshoot better than a 24" barrel? in .243cal.