The original Savage?Stevens model 311 shotguns were made from 1926-1945.The more recent made Stevens model 311 shotguns were discontinued in the year 1989.
I purchased my model 311 back in 1968, as a used shotgun. I was told it was factory made with no serial number. I dont know mfg date, but this will maybe start you in the back dating process.
The best that I can do is state that the Stevens model 311 side by side was discontinued in the year 1989.
No sn data in the public domain.
value of Stevens 20 guage model 94 F
Made in 1972, value round $80, depending on gauge and condition.
I can say that they were discontinued in the year 1989.
Manufactured by Savage/Stevens (equivalent to their Model 311-D) probably in the 1950's. http://www.e-gunparts.com has a listing of most house-brands.