Just noticed the closeups of the back of the lock. It looks like at one point in its life, the "ledge" on the back of the cock was built above its original level to realign the stopping position against the plate. This is often associated with early lock repairs where the cock was replaced with a piece from another lock - see Hamilton's "Colonial Frontier Guns" - there is a whole series of photos showing these types of repairs. Even on fine guns, the goose neck of the cock was a weak point prone to breakage. It could also just indicate that the mainspring (or tumbler for that matter) was replaced and the toe that rides against the tumbler now sat in a different position, necessitating building up the ledge to allow it to stop in the right place.
In either case, these types of early repairs usually indicate a period repair rather than a reconversion, so in my mind it detracts nothing from the appeal of the piece - instead, it sort of enhances it a bit as it shows more history. If the cock was replaced we are lucky the mainspring did not bust out through the bottom of the lock mortice - we would not have this fine piece to study today if that had happened.
Guy
