I have a European O/U shotgun/rifle, with an integral rail of 16mm across at the rear end of the barrel. There is no X channel for a bar to tighten a' la Weaver. It would be great to be able to mount rings that will grab such a base, but I cannot find any. Do you folks have any ideas??
Thanks
Alex

i have done this in 2 ways. 1 by milling a grove on the sides so the rings would grab (be sure the rib is solid not hollow before doing this) and #2 by taking a separate piece of steel, milling a notch out that would sit over the rib and be attached by set screws, then milling in the groves for the rings