I use B-Square Weaver adapters, or their Chinese knock-offs, with whatever brand of Weaver-style rings seem appropriate if they will work on the rifle in question. Sometime they don't work because of the design of the grooves, particularly on some of the old, 1960's and 1970's vintage, Mossbergs, like the 340/640, and Savages, like the 63 and 65.
