Just my opinion but this rifle, the “Petersen” rifle and the Atchison Rifle (the silver mounted J&S Hawken) are important examples of the evolution of the Hawken Mountain Rifle. All three, IMO were stocked by the same hand, surely Jake. I am sure the “Petersen” (from the owner at the time of Bairds first book) and Helena J&S were taken to and used in the Rockys by a “mountain man”. The later Hawkens, such as the misdated (IMO) Modena rifle, the Bridger and the Carson are all later, Army Scout or Wagon Train Guide era rifles. I believe the Bridger rifle is an off the rack rifle he bought when hired to guide an Army survey party in the 1850s.
Poster RAT has done yeoman work on research on the Helena J&S, something I lack the patience for.
Just my 2 cents.