I inquired about them from Winchester Sutler, sent 4 emails, no response, finally called and talked to a fella that didn't seem all that interested in selling them when I asked for details about mounting one on my 38-55 Target, he later responded to my email(below), but I gave up on them due to his lack of offering more info on the product he was selling. You'd think that since they list the rifle model, they would know exactly what mounts it would take!!
The link OSOK posted is in the FAQs, but it doesn't appear to be any good right now, here's their website, scroll down the page to the scope pic.
Tim
http://www.winchestersutler.com/Spoke to you this evening but I feel that you're disappointed in answers. The reason for your confusion or our incomplete information is that the sight is geared to persons familiar with mounting scopes on vintage rifles. There ARE no specific instructions. The company that makes these in California, doesn't give out more specific instructions because of this. None of these scopes lends itself to a "bolt on" type of arrangement but do require the services of a gunsmith for installation. Thus, my reply to you about picking out a scope and we would pick out the correct fittings. One thing I do need to know if you decide to go this route is weather your barrel is round or octogon. I hope that all of this helps. If you have further questions, please do ask. Best, Tom