While i do not consider myself the expert on French guns,i have been called an expert by an expert.So take it for what it is worth.
That lock is not French,its more Germanic than anything.contrary to the what the vendor that sells it says.i want to see the original.
The BP, TG& SP are of the DE CHasse style. And as Mike said they were made but we have no existing/known pieces.Bouchard's book makes a reference to brass trimmed FDC's being sent to NF.
As to the RR pipes, most if not all were simple sheet metal pipes with i simple filed line at each end.Thumbpieces were not found on these guns,as were not turtle front sights and surface mounted buttplates.
keep in mind this was a gun made for the Dept of the Marine[Navy]modeled after military arms of the day[a sporterized verzion if you will]made for military use and to help arm the allied natives. It does not much follow the styles[artistically of civilian armsThe FDC does appear on a few tradelist/inventories.It actually is its own type of separate animal as far as French smoothbores go.
i hope this is of help.
Alex E.