The stress to the action is based on pressure --- pure and simple. Since the cartridge case can't possibly contain the burn pressure, the head of the case must be supported by the action face. The breech and bar carry the back thrust, and opening moments (force acting at a distance) are carried by the hook/pivot pin and the bolts and bytes. Pressure acts on recoil only as it causes acceleration of the ejecta and the resultant muzzle velocity.
Free rearward acceleration of the gun is identical to the acceleration of the ejecta, only opposite in direction. Since the gun has no non-trivial moving parts, recoil is identical to the ejecta mass and the muzzle velocity. Recoil is absorbed by the shooter via the stock. So, recoil is the factor for stock/shooter abuse.
DDA
