Nothing different externally about the metal. The serial number would not be specific other than to the correct time period. My guess is about 1985-95 but I would need to research to be certain. What was done to "Laserize" a gun seems to be unclear as well. Some say it was just a heavier spring and specific lubrication. Others claim that there were special treatments inside the compression tube ranging from improved crosshatching to nickel plating. I have not yet found a definitive way to prove other than the serial number range and the medallion. Since yours is stamped San Rafael it was likely done in Santa Rosa either as a retrofit or as a new gun with the previous stamp.
I bought a new HW77 from the Santa Rosa store that was brought to the new location when they moved from San Rafael and was stamped accordingly.
