BillK,
Your chances of finding a scope to fit this rifle are pretty much "slim to none". However, your chances of having a pair of modern rings modified to fit, are pretty good. I don't remember seeing a mount base with the "stop" like on the front of this one before, but this general type of rail mount is not too uncommon. I suggest you take the rifle to a good gunsmith with a milling machine and have him modify a set of Ruger, Warn, or similar modern quick release type rings to fit. There may be issues with the width of the dove tail, and it may be tapered, but he should be able to work them out. Another likely problem will be eye relief with the particular scope and for this reason, I suggest you ask the gunsmith's advice before buying one. If it is a hammer gun, he should ensure the ring height is enough to allow you to reach both the hammers. The round cut on the base is to lock the rear ring by having a "flat" on the shaft of a lever that slides over it and then rotates the rounded part of the shaft into the cut. It is important that the rounded part of the shaft be thick enough that the lever cannot turn all the way down. In other words, the shaft must "bottom out" in the cut instead of the lever stopping on the base. Good luck.
Mike
