Serial #376612 in 38 spl with a 6"bbl. It also has a 3 digit number stamping that I am curious about. "846" is stamped underside of the bbl right next to the frame (covered by the ejector rod when the cylinder is closed) and another "846" on the front left side of the frame near the grip bottom forward of the pin to fit the grip hole.....covered when the grips are in place. Is this to match the bbl to the frame... or something else? Your input is appreciated.