thinking about this topic. If anything the Benelli inertia system will work because it requires energy to operate the system. it needs 180 kgm of kinetic energy for a 12 ga at minium. holding it against an unmoveable object will significantly increase that number. You probably would not damage an auto loader gas or inertia as the energy generated is used to operate the system. But on a pump or a rifle you can crack the stock. I saw it happen to a rifle when the lead sled had three 50lb bags of lead shot on it. in any event, it is a foolish thing to do to a fine firearm.