Only 36 Grade 1 20g with 26" barrels were manufactured.
Unfortunately, information on shotguns produced 1890 to 1917 is usually limited. Generally, the shipping records include only the shipping date, manufacturing date, barrel length, gauge, and grade.
But you might get lucky with the original purchaser in a Research Letter
https://lcsca.clubexpress.com/conten...dule_id=245742
The FW frame was introduced with the 20g in 1909. There MAY be a few 20g guns made prior to then on a Regular frame, but no one, other than Pine Creek Dave
has seen one.
Hunter Arms did not lengthen the 20g chambers from 2 1/2" until 1936.
The No. 1 was discontinued when the Trap Grade was introduced in 1913.