No way to answer without knowing who made it and the serial number.
You need to provide the serial number
Ithaca made 10 gauge shotguns.
Most likely the 50-60's
If you have a Browning auto-5 shotgun in 12 gauge it was made in the year 1925.If it is a 16 gauge shotgun,then it was made in the year 1929.
If your shotgun is in 12 gauge,then it was made in the year 1922.If it is a 16 gauge shotgun,then it was made in the year 1927.
If it is in 12 gauge then it was made in the year 1928,if it is in 16 gauge then it was made in the year 1936.
If your question is about a Browning auto-5 shotgun in 12 gauge,then it was made in the year 1925.If it is a 16 gauge shotgun,then it was made in the year 1929.
If your Browning auto-5 shotgun is chambered in 12 gauge then it was made in the year 1928.If it is chambered in 16 gauge,then it was made in the year 1938.
1951 was the year this gun was made
If you have a Browning auto-5 shotgun in 12 gauge then it was made in 1927.If you have one in 16 gauge then it was made in the year 1931.
That all depends on the gauge of your auto-5 Browning shotgun.If you have a 12 gauge,then it was made in the year 1921.If you have a 16 gauge,then it was made in the year 1927.
Try the library and old gun catalogs.