Drew, those are good pictures.
Firstly, I have never seen a Folsom made gun with Damascus or twist barrels. Interesting [to me and about 5 guys in the world]
Secondly, your observance of the firing pin retaining screw is accurate. The interior edge of the sideplate retained the firing pin in the Model Nineteen Nine the L Trap Grade you show. All other L Trap Grades I have seen had the typical Baker Gun and Forging Co. firing pin retaining screw. The Batavia Leader in the 50,000 range that originated this post would also retain the firing pin with the inside of the lock plate. I would guess that it looks like this one from my group.
