Used to use them a lot, a very good mount, probably the best at matching surface to surface with your scope. I've seen them hold heavy scopes, on hard kickers without fail. Don't mix and match pieces, don't over tighten. The only drawback, is if your like me and a bit shortchanged in the dexterity department they are a bit more difficult to mount. So if you move scopes back and forth a lot, it's a bit of a pain.