This is in the private collection of a friend of mine.
Octagonal, slightly tapering towards the muzzle, this barrel is remarkable for having an earlier touch hole nailed up and a new one, with a surrounding funnel shaped trough, pierced on what now seems to be the top flat.
Originally, this item, too, would have been fixed by two iron bands to a wooden stock. There is a high probability why there are still so many similar early barrels around. My theory is that most of them were part of multibarrel organs or devices:
Attached please find an illustration by Konrad Kyeser, Eichstätt, Bavaria, from his work Bellifortis
(The Strong One at War), 1405, depicting such a rotating multibarrel device, and two samples of the earliest shape of a rectangularly curved igniting iron: