Well, since like certain parts of our anatomy, every bodies got one. My opinion leans towards Murphy’s gun being a side-by-side double. My reasoning goes like this. Swivel breech guns were all the rage at the time the details of the event was penned, but not so much when it actually took place. And, few actual survivors of the event were still living when it was penned. Side-by-side double smoothbores were relatively common during the period of the actual event. Common enough that a few Indian trade guns were built in this format, and a gun built with rifled barrels would’nt be a big stretch to imagine. Or, a big engineering project for a competent gunsmith. Another reason for my belief is a Swivel breech would be a two handed process to index the second barrel, while a side-by-side would not. Remember Tim supposedly shot from a perch in a tree. A side-by-side could be fitted with a set of sights on each barrel, sighted in for different ranges making it easier to gauge such a long shot (I know this is also possible on a swivel breech). I also think a double would be less likely wear, and get loose, in a combat situation, than a swivel. Oh, and by the way, there is some evidence that a rifleman named Young actually made the shot rather than Tim Murphy.
Hungry Horse
Hungry Horse