1926
1953
We can answer it here on Wiki, or you can go to the Browning link below.
Browning's web site has a sn search function.
fn a5
In order to date your Browning 20 gauge shotgun you will need the prefix to the serial number it should look like a number followed by the letter Z.or 2 numbrs followed by the letter X.
Blue Book of Gun Values, call browning.
Contact Browning customer service through their website.
Go to Browning's site, Support, Date Your Shotgun.
As you listed it, the sn does not make sense. Go to http://www.browning.com/customerservice/dategun/detail.asp?id=13 and you will see what I mean.
see the Browning website
It was made in 1968
1928