Heavy objects have more inertia than light objects, which means they resist changes in momentum. Force is equal to the rate at which momentum changes in time. So for a given force, the light and heavy rifles will both gain the same amount of momentum in a given period of time, but the lighter rifle will accelerate faster to gain that momentum. If the rifle/scope is accelerating faster, then there is more force applied to the internal parts and fastening systems.
But heavier scopes will have heavier internal components, meaning that they offer more inertial mass for the recoil force to act against. That creates more stress on the internal mounting mechanism. So heavier scopes suffer more internal recoil stress. Right?
