Scientific proof? How about, "For every action there is an equal and opposite reaction."? When a cartridge ignites, the case expands to temporarily grip the wall of the cylinder. The recoil force is transmitted to the cylinder, which is slammed backwards. Since there is already, and necessarily, a certain amount of fore-and-aft and side-to-side play built in to the system, the parts that hold the cylinder in place are slowly but progressively battered. Over time, the small tolerances built in to a new revolver thus get larger. Eventually, endshake and rotational alignment go out of whack and parts involved in controlling those aspects of operation must be replaced.

__________________
Pisgah