[Philip]

The illustration in Stone, and my recollections from handling the piece, indicate a very rudimentary mechanism (which is unfortunately damaged at present, the serpentine is separated from the gun). The trigger hangs from a pin driven transversely through the stock, through a neatly-chiseled rectangular mortise opening on the underside. A piece of cord, tied through a hole at the approximate midpoint of the exposed part of the trigger, attaches to the shank of the serpentine which is located ahead of the trigger by a few inches. Serpentine rotates on a pivot pin, and swings back (towards shooter) to reach the pan. So pulling the trigger back also moves the serpentine backward via the cord. It doesn't get any simpler than that. I did not see any provision for a return spring for either trigger or serpentine, as would be the case with a European sear-action matchlock, or a Turco-Persian style lock (common also in India, Tibet, and most of China).

So presumably, the shooter had to manually reposition the serpentine in its forward, away-from-the-pan position after shooting. I remember it being fairly loose on the original gun, but for safety and ease of handling, the reproduction lock should have a modicum of "tightness" to the pivoting action so the arm (and lit match) don't go flopping back and forth as the gun is handled in the field. This is also a consideration since I don't recall there being a pivoting cover attached to the pan. The degree of pressure holding the serpentine in any given position should not, of course, be enough to make operation of the trigger inconvenient.