Looking at this gun, and knowing that John Brown was traveling from TN, leads me to imagine (just speculation of course) that he carried a typical 1800-ish TN rifle probably of smaller bore with him to St Louis, and at that point, sold or traded it and told the Hawkens 'Make me something like this, but bigger and stronger!' That's exactly what it looks like to me in almost every way. Including the forearm shape. I like it a lot!