researching grandfathers 1100 16 gauge but need help with barrel codes and serial number: I fired this gun twice in my life: 1st amusing my grandfather when quail hunting at 10 or 11 years old (1970). 2nd: at a college skeet range (1980). Have not fired this gun in 43 years. My issue: identifying it.
barrel left side I see NA MZ
serial number 165231W
anyone really familiar with how their codes work I would appreciate some feedback. I'm guessing this is somewhere around early 1968 but he may have purchased it a few years earlier.