Hello, John -
If you have not yet discovered the L. C. Smith Collectors Association web site, then this is the link to the association home page:
Reading the association's article here may prove instructive about your shotgun:
On the association home page, in the left side bar, scroll down to the link for Shotguns. Through that link you will find a link for Year of Manufacture. Click or tap on that link.
On the web page for Year of Manufacture, near the bottom, you will find this sentence:
To obtain all of the existing information about your shotgun, the Research Division of the L.C. Smith Collectors Association can search the factory production records and can provide this information in a letter.
There is a charge for such research, however.