The notion that the Rossi Puma M92 in 454 Casull has undergone a "special heat treatment", sits clearly in the category of "Gun Folklore". I imagine someone once thought "it must be different from the other Rossi M92's due to the much higher pressure of the 454 Casull" and because upon inspection it appreared identical to one chambered in 45 Colt, it must have the "special heat treatment". That's very commonly used "logic".