about 1925
Your serial number indicates that your Ithaca shotgun was made in the year 1920.
It sounds as if you have a Ithaca Crass model shotgun,that was produced in the year 1903 by your serial number.
Impossible to answer without the serial number
1924
It was made in 1919.
1905
612
5 years
Impossible to answer without the serial number
With the serial number that you provided,your Ithaca double barrel shotgun with the damascus barrels was produced in the year 1900.
A model 37 with the serial # 10464 was produced in 1939.
It sounds to me that you have a Ithaca Flues model double barrel shotgun.With the serial number that you provided,your shotgun was made by Ithaca in 1917.