(1)If the question is a general one, I agree with the words above. If the question relates to a fatigue critical part, then tests should be run with different shot sizes, intensities and coverages as well as shot hardness under service conditions of temperature, stress, etc.
(2)Recognize that normal hardness cast steel shot work hardens in use beyond the delivered HRc 45-52.
(3)Shot softer than the part can still produce surface compression - hardened gears, for instance
