At some point he carried a Hawken Rifle (a couple unverified sources), possibly built by Sam before he got into business with his brother.
There is some minimal evidence that Sam built some rifles for Gen Ashley as early as 1822, three years prior to the J&S days (in 1825), and that some of these rifles were used during the exploration of the Missouri river by Ashley's employees.
So it's possible, if all that is true, that Smith came into possession of a very early St. Louis, Sam Hawken rifle.
There was a rumour that the Santa Fe Hawken built by Western Arms was supposedly a copy of the Smith Hawken, but that turned out to be more wishful thinking than fact. It was of a much later style than Smith could have owned since he died in 1831, quite a while before the Hawken Plains rifle style came into full being.