According to the serial number, you have a Crass model gun. The manufacture date is around 1898. Check out www.ithacagunrepair.com.
Your serial number indicates that your Ithaca shotgun was made in the year 1920.
With the serial number that you provided,your Ithaca hammer less double barrel shotgun was made between the years 1904-1907.I could not asses a value of this shotgun without a brief discription of its condition.I will say that most shotguns of this age and make will bring in the neighbor hood of 400 dollars and up.
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
about 1925
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.