I can say that they were discontinued in the year 1989.
I can say that the Stevens model 311 has not been produced since 1989.
Very likely produced in the 80's, as this was the last model and production stopped in 1989.
The Model 311 is essentially the same as the Model 5100 which was identical to the Model 5000 which was really no different than the double barrel shotguns being produced by Crescent Fire Arms before that company was bought by Stevens.
Possible special order.
You will have to contact Savage directly for the answer to your question.I beleive that the serial numbers to the Stevens model 311 side by side shotgun are not in the public domain.I can say that the model 311 was discontinued in the year 1989.
There is no website to determine the age of a Stevens 311 by serial number. However, since yours has a serial number it is almost certainly post-1968. sales@countrygunsmith.net
Possible special order.
Series H
50-200 USD
50's-60's; 75-275 USD
this was made either 1988 or 1989.
Just sold one for $750.00/ like new