I have hesitated putting this in...but here goes. At one point in time they made metal replicas of Doc Holiday pistols that would actually work. The grip on this gun brought to mind the look of one that my brother had when we were growing up...it actually worked as a real pistol. I don't recall his saying D O C specifically.) DOC on the gun may mean something else, but it just kept bringing to mind those old guns. They have an authentic gun on vintageweaponry.com/revolvers.htm, the 6th one down, by Merwin Hulbert that refers to Doc in the info...and the grip resembles that of what I remembered. I own pistols but am not a collector nor an expert.
Just another venue you can explore!