My brother just bought a Stevens model 940 at a gun show this morning and we can't find any information on one of the barrels that came with the gun. It has a 20ga barrel installed and came with an extra barrel that is marked as a 9mm RF and the barrel is rifled with rifle sights installed. The barrel release lever is on top of the receiver behind the hammer. The 9mm RF barrel fits the receiver and locks up solid, the frame has only 1 firing pin and no other type of selector. I have searched the net with as many different configurations but have came up with zero information on this odd barrel. The only thing I can come close to finding is a 9mm shot shell. I'm curious to hear if any of the many knowable members here has any information on such a barrel made by Stevens. See the attached pictures. Thanks in advance for any light you may be able to shed on this barrel.