Model 1100 Issues with Receiver Date Codes

[Scorpion8]

So I picked up a "minty" 1100 12ga with a 26" skeet barrel. No dates codes on the barrel, but that isn't always an indicator. My issue the receiver dates codes shown on most informed sources (!) show the serial number prefix with L=69, M=74, N=78, P=85, R=90 and then always states "repeats in sequence" or somesuch. Trouble is, there is no sequence there. That list has gaps and inconsistencies. M=74 to N=78 skips 4 years, P=85 to R=90 skips 5 years with no value for Q. In any event, my serial number is "NxxxxxxV". The N would indicate 1978, but this gun is mint. 47 years old and nada for wear, tear and heartache?

Please advise. What year was my new 1100 score made?

[Scorpion8]

Any help please? Seems like it shouldn't be this difficult if there is an explanation.

[Scorpion8]

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