FWIW - ORIGINAL Hawkens, those by Jake and Sam that is, were:
1) Barrels: blued - rust blued not fire blued
2) Locks, breechplugs, and the iron mounts such as butt plates, triggers, trigger plates, and guards were case hardened (IMO generally not color cased although case colors can/do fade over time and with wear so they may have been color cased).
Those processes were not only used by the Hawken Brothers, but were the most common finishes on rifles of that period....
Over time many have come to look as if they were browned (rust bluing is after all a form of browning and some may have been re-finished)- my observations are based on the dozen or so originals I've seen first hand (and handled - including my favorite the Modena/Medina rifle) and also in talks with Don Stith and others who have exammined/disassembled even more than I have.........