There's a list of serial numbers by year at http://ithacagunrepair.com/page5/page23/
If you are referring to an old double barrel, it was made in 1919.
If it's not immediatley apparent, you won't.
50 years old
HAVE IT CHECKED OVER BY A GUNSMITH FIRST!!!!!!!!!!!! It is an old shotgun.
You lick it.
Odysseus dressed up as an old beggar when he returned to Ithica.
Made in 1969
Try e-gunparts.com
$50
The gun was made in 1915.
If it is a 12ga, it was made in the early months of 1940 auto5man
Impossible to answer without the serial number.