Whether or not you want to worry about such things is up to you. Despite the rumors, if you build a fusil yourself that somewhat resembles a period piece, most guys will tell you, "great looking gun, well done!" If you persist and ask, "is this detail correct?" then you may learn a thing or two but it should not spoil the joy you have in your gun. If you REALLY want to recreate an original, there is no easy formula, like, "Take a L&R fusil lock, this wood, that barrel, this sideplate and buttplate and trigger guard and you're good to go." If you want to go as far as you can in evoking an original, it requires effort and study, traveling and research. We're spoiled by thinking kits will be just right and all we need to do is assemble and finish and let them do the homework for us. There is no market large enough for French fusils of a particular type to justify production of a lock that fits "perfectly" for that purpose and no other. There are a number of locks that can be adapted with little work to be as close as anyone would want.