2-Piper,
The net is sprinkled with clips of people firing zip guns made with two sections of pipe and they hold OK. Richardson industries even offered such a gun which was basically two pipes fitting into each other with no bolting of any kind. You might be surprised as to how an A-5 would behave if fired unlocked. Provided the chamber is not highly polished I would be willing to fire one, you can watch from a safe distance.
Frame cracking occurs, I have photographed a few such accidents. The question is why the frame broke, because it was pushed back by the cartridge head alone? Has anyone ever figured out the Poisson effect and its contribution to the firing cycle of a shotgun barrel? The Poisson effect covers the radial expansion and axial contraction of thick walled cylinders under pressure. The breech end of shotguns falls within the definition of thick walled cylinders. Can such rapidly developing dimensional changes, even though small, affect a shotgun action? If so how?
How come some US made doubles with apparently weak lockups (L.C.SMith, Lefever) hold up over the years when triple bolted doubles shake loose?
These and other questions are puzzling. If some high speed photographers could film the action we will get an idea of what actually happens during the firing phase and the recovery from it. But most of them prefer filming more sensational shots of the shot exiting the muzzle.
