What is the age of a Mossberg New Haven 600AT serial number G877819?

To determine the age of a Mossberg New Haven 600AT with the serial number G877819, you would need to reference the manufacturer's records or a reliable database that correlates serial numbers with manufacturing dates. The "G" prefix typically indicates that the shotgun was produced in the late 1970s to early 1980s. For a precise year, you may need to consult a Mossberg expert or reference gun collector resources.