Sir I believe it is you that is intermingling the two separate forces.

Chamber Pressure acting upon the interior of the barrel, chamber and ejecta versus a totally separate force called recoil which has resulted from the ejecta being discharged from the barrel with an extreme amount of velocity (Newtons 3d law of motion. Remember recoil is totally independent of and not related to pressure. Recoil is only dependent upon the mass (weight) of the ejecta and the velocity of that ejecta as it departs the confines of the barrel. There is no transfer of the pressure forces outside of the chamber except for the expulsion of the ejecta. It is the force of recoil that causes the mechanical actions (back thrust, torquing of the frame, deflection of the barrels and transfer of force from the barrels through the frame to the stock that produce what we are referring to as wear.