Welcome to the board.
A splendid article and photograph in Double Gun Journal Volume 15 Issue 4 Winter 2004 by our member Jeff Stephens lists in Part II of his series some of the information you're looking for, including a photo of a 20ga Grade 1 serial 134, 565 made in 1907. From selected numbers appears yours was made circa 1929-30.
Mr. Stephens' article in the DGJ Summer 2004 Volume 15 Issue 2 has a valuable "Primer On the Scalloped Boxlocks" with great pictures and detailed information on production and models. It includes a photo of a Model 40 in 20 gauge. Please let us know what you've got. Mr. Stephens will be interested in your information.
Last edited by King Brown; 08/07/07 09:25 AM.