I'm reading a book on Big Foot Wallace who was more of a Texas Ranger than a mountain man however the time period (at least in his early years) is about right. There is a photo and he has "Some sort" of long rifle. He came west from Virginia. IAE, this idea that everyone carried a Henry Flintlock or Hawken percussion, it seems the most common rifle was of some obscure make. It would be interesting to do research on all the known rifles carried by various mountain men.