I wasn't happy with a saddle-type mount on my SBE. I tried it for a few years and it damaged the finish of the gun. I didn't have any regrets removing it and having SBE drilled and tapped for a Trijicon Reflex. It's a dedicated turkey gun. If your M-2 has a vent rib, perhaps you could have an existing cantilever system modified and clamped to the rib. The best solution is drilled and tapped receiver, but for some reason you don't want it done.