When you install a scope, the effect is a increment in the "system weight" (and inertia), the heavier the scope and mounts the bigger. Your rifle will be heavier, and with the same force trying to move the shooting barrel, the net result will be your SxS double will cross the shots a little more. The magnitude of this change will depend of many factors, of course. In my own Merkel 150 9,3x74R, with 250-260 grains bullets, the rifle will cross the two shots 1-1,5" al 50 metres. Hope this will be useful.
