I believe that PO Ackley also took an Arisaka bolt action and progressively reduced the barrel thread diameter while firing factory ammunition to prove that a dry non-lubricated chamber and cartridge together resulted in virtually no back thrust. He continued until there was basically no thread remaining and the barrel never moved.

Another experiment was done with a shotgun which was held upside down with the top lever held open and the barrels did not move away from the action when firing, the weight of the barrels being enough to hold the action closed.

Matt.