Probably a lot of locks that showed up in the early days of percussion were of the "flint persuasion" whether "re-purposed" or simply had plates built that way because "that's the way they knew how".
If you look at John Armstrong's locks, which he built himself, and his building straddled the flint to percussion transition, the plates look pretty much the same whether flint or percussion. He may (unknowingly) have built the first "interchangeable" locks for swapping flint and percussion
How many were flint "before" they were installed but "converted" for the build, compared to how many were "installed" as flint and later converted is often the point of contention.
The lower pictures that show the trigger guard are almost carbon copies of the trigger guards (made?) used by their father Christian. He wasn't fussy about many things - any lock/trigger was fair game, but his trigger guards were pretty much the same rifle to rifle.
That guard would have been "home" on one of his Maryland rifles. To me that may tend to indicate that at least that lower rifle pictured is the type of rifle I would expect either of the brothers to build until they fully developed their mountain/plains style.
Also looking over the pics (again), the "lower" rifle has an earlier breech than the upper one (or two).
I have a decent article on the early snail where it is suggested that the "early snail", which looks like a comma was used between 1835-43 which may allow you to date the rifle "somewhat".
