I recently acquired a perazzi mt6 combo set (single barrel and over/under barrels). The owner is deceased and his son knows nothing about the gun. The receiver appears to have a nickle or similar finish. The research I was able to do on my own suggested that the mt6 first came out with grooves on the side of the receiver and that a later version had a blue finish. I was not able to find anything that mentioned a nickle type finish. Therefore, I am unclear if the finish is after-market. Also, if it is after-market, is my best option to send it to Giacomo in New York to be re-finished blue? The barrels, stock, forend, etc. are in top condition. I would appreciate any help on this issue? Thanks in advance.