Chris carries a blued Colt Model P, with a 5 1/2" barrel and stag grips, for a sidearm. His rifle is a Model 1866 Winchester (the "Yellow Boy").
Colt SAA
Winchester 1866
Notes:
The Model '66 was chambered to fire the .44 rimfire.
Due to the time period the show is likely set in, Chris' Colt is probably a .45--the Colt Frontier Six (.44-40) was not introduced until 1878.