You evidently do not understand "proof loads". A proof load is NOT meant to determine whether or not that load will blow up a gun. That would determine whether that load is over the Ultimate Strength of the metal. A proof load is meant to determine whether the load exceeds the PLASTIC Strength. That is the point where the stress exceeds the point where the metal will return back to the same dimensions. To check this, the proof houses take extremely accurate measurements in specific areas before and after the firing. If there is ANY dimensional change, the plastic deformation has been exceeded and damage has been done to the gun. The gun has failed proof test. Your plan does not do this. You may do gradual damage to your gun which will possibly destro it after several shots when you mistakenly believe it is safe to shoot.