I guess it could be a factory upgrade. As I recall, the Custom Shop was pretty heavy handed on the engine turning when doing upgrades from Field Grade. It's hard to do vivid engine turning over stampings without losing some of the definition of the stamping. Again, I would go back to Cody with a request for more information. I once got an unsolicited letter from Cody a year after the original letter about the installation of a second set of barrels for a 21.