There are a couple of Yt videos showing doubles in slow motion during firing. There is obvious movement in the top lever in one case, a Citori, and in the hammers of a muzzle loader in another. The Citori top lever can be seen oscillating during recoil, and that oscillation most likely is due to more than just worn locking botl angles. I will post links when I find them.
Apparently inertia forces play a role in the movement of bits during recoil, both in the rearward phase as well as in the braking phase when the gun stops on the shooter's shoulder.
