Late, but that's an amazing find you've got there. Those were very fine scopes with exceptional clarity and sharpness of focus right out to the edge of the field. The brass ring lacquered black was probably put around the one tube to hide the hacksaw cuts where the original rings were removed. A gunsmith or owner who was not able or willing to take the scope apart so as to unsolder the rings from the tube, would have to cut them off in this way.