Metalguy

It is not the pressure per se that is the imroptant factor. You need to know the MAP for the two cartridges and the base diamiter that the pressure works on in the two cases.

so R1xR1xPyexMAP=breach thrust.

Now you need to compare that to the thrust for 12 gauge cartridge that was the origional chambering.

What you need to bear in mind is that the action is goint to try and bend around the root where the standing breach meets the watertable.

If you want to do the clacs properly one should also consider the moment of the force as a smaller diamiter acts lower down the standing breach and reduces the force acting on the root.

The hoop pressure ie 47,000 v 42,000 is relitivly uninportant as the barrels steel (if the gun is properly assembled will happily take twice that pressure.

Regards