It is hard to know the thinking at the time Bob. Something to think about is this: when a cock stops on its shoulder on the edge of the plate, there is a terrific tendency for the top of the cock with the screw, top jaw and flint, to keep on going. Many flint cocks are broken in the neck because of this. The reinforced cock was the answer to this problem, or at least, it certainly helped. The bottom jaw of a reinforced cock does become battered by striking the fence, and the tumbler bridle inside the lock takes up the energy too. But that's the way they did it.
The conversion of the Smithsonian rifle is as rough as it could be...definitely not the work of Sam Hawken. Also, I find it almost unbelievable that Sam would use an old lock plate to make a new rifle, when everything else on the rifle is of such expectedly high quality.
Don, I hear you being inconclusive as to the original ignition system of this rifle....Myself, I'm satisfied that the rifle started life as a flintlock.