Appreciate the replies.
I do suspect getting details on a very early St. Louis Hawken is going to be a stroke of luck at best.
I'm looking in that gray area between when they would have definitely been building Maryland styled eastern rifles and Plains/Mountain style which had evolved, at least to the point of recognition, with the Atcheson rifle known to have been built in 1836.
The two I mentioned above were simply a pair of "known to most probably be" percussion rifles that could have been built at the very start of the "wide" availability of caps in St. Louis (1830-32) and points west (at least in significant enough numbers that one would consider carrying a percussion rifle that their life may depend on).
Over the course of trying to track down examples of these rifles I am finding that Sam was "somewhat prolific" in building rifles in the few years he was in St. Louis "before" he partnered up with Jake. So during the period of 1822 to 1825, Sam alone may have put a good number of "St. Louis Hawken's", albeit Eastern style, into the hands of trappers.
Anyhow, the search continues