Sent my request to Havlin, got a reply back from Cheryl the same day.
Model: Mossberg 500AB
Serial Number: C111xx
Response: "I can't give you a date but I can give you a year range of 1971-1972. The A B C & D serial numbers date from 1969-1972 and were only 5 digits following each alpha character. They soon realized that they were going to run out of alphabet and switched to 6 digits in 1973"
Hope this helps out the list.
-Ant954
Model: Mossberg 500AB
Serial Number: C111xx
Response: "I can't give you a date but I can give you a year range of 1971-1972. The A B C & D serial numbers date from 1969-1972 and were only 5 digits following each alpha character. They soon realized that they were going to run out of alphabet and switched to 6 digits in 1973"
Hope this helps out the list.
-Ant954