Proofhouse.com has a store brand conversion chart that might help.
Marlin
Your western auto model 312AA shotgun was made by mossberg for western auto.The mossberg model 395,395K are the mossberg model designations for your shotgun.
Mossberg
savage made this model,orig model is a 77
It was made by Savage for Coast to Coast. It is a Savage Model 58.
Savage Stevens
Being that you said auto shotgun,then you have the Browning auto-5 shotgun that was made by FN in Belgium from 1903-1975.Your serial number indicates that your Shotgun was made in the year 1938.
$250
Stevens, as their Model 94.
Odd question... It's a auto-loading shotgun made from 1905-1947, actually it is the FIRST auto-loading shotgun produced in the U.S.A. !
your browning model auto-5 shotgun was made in 1924.
If your shotgun is chambered in 12 gauge,then your shotgun was made in the year 1913.If your shotgun is a 16 gauge model,then it was made in the year 1926.
The Auto 5 model was made between 1903 and 1998