IMO:
That is one handsome (for the period) unreconstructed rebel. I really like that picture, especially if it your GGGpaw. You had better make copies of that because it is irreplaceable.
I have taken liberties to reverse the photo image and to enlarge it a bit.
#1) It is not a Walker: the cylinder is too short and there is too much cylinder gap between the cylinder and the barrel frame lug. The load lever is not a pointed Walker and appears to engage a barrel catch. The trigger guard appears to be rounded at the rear, and all manner of Walkers (Whitneyville and others) have a squareback trigger guard. All Walkers had the wedge entering from the right side of the pistol.
#2) IMO, although the photo is very poor, it appears to be a 3rd model Dragoon .44. It appears to have a round to octagon barrel juncture, a round trigger guard, and the proper spacing between the cylinder and the barrel lug.
#3) The barrel wedge appears to be
huge and in the white. I do not think that during the War that some wedges were
not lost, and this may be a handmade wedge from convenient piece of steel. If so, very good campfire craftsmanship.
#4) I think it to be too small for a Colt (or copy) 1851 Navy. The soldier in the pic has big mitts which would swallow an 1851. He is also left-handed.
#5) It also appears that the cylinder stop slot has a round/oval shape so that brings about another Q that another poster posited: is this a prop gun just for photographic purposes? If so, this pistol may not even fire and may just be a prop.
I would cherish that photograph and keep the original as safe as possible.
Thanks for posting. We are all enriched by that photo. I am a Civil War buff, and do not take sides insofar as why it was fought. To me, it is a study about how modern technology at the time overrode Napoleonic tactics and changed the face of war forever.
Jim