Lyn,
I wouldn't put too much "stock" in my 1913 Deathhead (#1612) having a stock lug.
...the serial number is way too early to have one. Although the frame and barrel numbers match and appear to have been made with the same dies, the gun has a replacement side plate and a mismatched sear bar. I suspect it was made up from an earlier barrel/receiver and a later frame, made servicable (perhaps by the mysterious unit that applied the deathhead) and placed into service. The metal is in good shape but it has litte original finish remaining. It has seen a lot of use and I would love to know the story it could tell.