If you have a common shotgun made before 1968, there probably is no serial number to look up. If the serial number is not on the receiver some where; i.e., water table, side, bottom, somewhere; then it doesn't have one & that is as far as you can take the serial number of a shotgun made before 1968.
No published sn data in English
You can look up the serial number at Proofhouse.com
Proofhouse.com has sn data.
Open the barrels and look on the flat part of the watertable (the flat part of the frame where the barrels close up) or the bottom of the barrels for the serial number
Providing serial number information has been published, you look it up.
See related links for information and look-up table on the Remington Society of America.
look on the Side of the recevier there should be a Serial Number on the older Ithaca Model 37 the serial Number was stamped on the receiver by the magazine tune and Barrel . also if you take the barrel off on the bottom of the barrel you'll find the matching serial Number. then look up WWW.SURPLUSRIFLEFORUM.COM in their search engine type in ITHACA 37 DOM match your shotguns Serial number up with their chart .
You find a published list of serial numbers for the maker.
You find a book with serial number information and look it up. You find a book with serial number information and look it up.
Browning.com has a sn function on their web site you can use to look it up.
furniture serial
Generally Stevens and Savage shotguns work like this: A for 1949, B for 1950, C for 1951 etc. You can go to www.bluebookinc.com and look it up to be sure. It is free to look up the serial number/date of manufacture.