Mark;
Don't want to sound too picky, but that is the push button forend fastener. The Clamshell has a lever & works on the principal of the Deeley, though it is shaped differently on a Lefever.
My 10 gauge pivot opener is SN'd @10,115. It has engraving very similar to yours, also has the push button forend release. It has 32" Damascus barrels & weighs in at a full 10 lbs. Does your gun have a pistol grip & if so does its tang run all the way down to the grip cap?
Unfortunately, someone had "Blued" my gun, both barrels & frame prior to me acquiring it. I kept thinking I would properly re-finish it but never got to it. Incidentally, its chambers measure 3" long.
