SL, I think you have a point on how the barrel acts. I spent some time talking to a group of engineering students (one ME senior with fresh mech. of materials) about the likely behaviour of the chamber area under firing pressure and decay. They agree that it will not react strictly radially. However, we did not come up with any estimate of the magnitude of axial force. So, we all need to do a bit of research on this issue. Good thinkin' on this issue!!

DDA