12 gauge BSS were first made in 1971 and 20 gauge in 1972.
You will have to carefully note exactly how the gun is marked, first.
It is a shotgun with 20 gauges.
50-75
1949
what is 20 gauge shotgun with kk worth
20
Yes, there were several made, mostly by Mossberg.
Stephens
Savage Stevens
With the serial number that you have provided,your Winchester model 12 pump action shotgun in 20 gauge was made in the year 1930.
Do an internet search with the words Brazil, shotgun and 20 gauge'