Assuming that there is enough force to cam open a system like the Smith, would that not create enough force for the barrels to continue their downward travel until the forend iron smashes against the underside of the action body?

If we fasten an action in a vice how much weight needs to be put on the barrels to cam open the action?

https://youtu.be/U_2gNhjAkjo

Note around 0.50 seconds the top lever moving right and returning. That would be interesting to analyse, is it due to parts inertia or camming? Fascinating stuff.