Referencing Walt Synder's book, 'Ithaca Featherlight Repeaters' (an invaluable reference and available from Walt) you have a Trap Grade made in 1940.
Value would need to be determined from condition, whether original, re-do or modified. Certainly an original Pre War Trap would be a few $$'s. Pictures of the gun including checkering and barrel markings, beads are needed to help determine if an original 28" IC barrel. -Dick