Usually by the serial number. If no serial number, then by features
The last patent date will tell you that it was made that date or later.
If that is a US Patent, you can look it up on Google, and tell when the patent was issued, but it cannot date the gun- other than we know it would have been made AFTER the patent was issued.
You have to tell us who made it.
Sorry- no production date records. Best I can tell you it is likely that your shotgun was made for Western Auto by Savage.
1136
Blue Book of Gun Values will tell you.
Need serial number that is stamped on the gun to determine the date of mfg.
Made in 1969.
By the serial number.
The gun was made in 1908.
The gun was made in 1940.
This gun was made in 1950