Thanks Kuduae,

You are of course correct. Both the 1934 patent (as shown in both Crudgington & Baker and Dallas) and the Great Exhibition drawing (extract pictured below) show the double bite arrangement. Crudgington & Baker do claim that for unknown reasons Lefaucheux later abandoned the double bite for a single bite nearer the pivot pin. Another drawing of the Lefaucheux action, this one with a single bite, is shown in Greener's "The Gun and its Development" - not a particularly accurate source though.

Incidentaly, this discussion reminded me that I actually own a very worn example Lefaucheux pinfire shotgun with the double bite action, although I believe from its English retailer (Masu Bros) it dates in the 1865-69 period)

Regards
RJW

Extracted from the "Illustrated London News" July 3, 1851