Outstanding teamwork Fernando and Stuart!!! You guys are great, and this is what I always hope for around here...working together to solve some of these mysteries.
I can understand the dilemma Dave is experiencing getting the photos, and its great to have him working with us in adding to the descriptions concerning this marking. It's kind of fun in a way, sort of like police investigation going through 'mugshot' books

with the help of a witness. Definitely interesting!!
Fernando, thank you for the well explained comments pertaining to the shortening of gun barrels. After reading that it reminded me of the Snider-Enfields where changed to breech loading they removed a section of the barrel at the breech to open for insertion of the cartridges. Good notes on the shorter guns for private defense also, and agreed they still would be a bit unwieldy as 'concealed' weapons with these barrels.
On the note about the spear holding figure, in "Armourers Marks" by Gyngell (1959) on p. 39, where one marking is of a warrior standing with what may be either a gun or a spear held in his right hand, attributed to Hoppe of Solingen c.1630; another by H.Michael of Munich c.1670 holding also in right hand some type of shorter hafted weapon.
These are supported somewhat by the markings with similar theme added by Stuart, though these seem more stylized figures holding halberds, and the bloused pantaloon costume of European fashion seems apparant.
These images are clearly intended to represent native figures, most probably of the New World and impressions of the so called 'savages' encountered in colonial settings. Europeans were intrigued by the 'wildness' of these new civilizations and the markings reflect this interest by the suggestion of power implied by the representation of these warriors.
It does not seem unlikely that the use of these figures might have been applied to trade weapons or materials intended for use in the Colonies or in dealings with the Native Americans. As mentioned, with the demand for materials for servicing weapons and more weapons were needed, any components at hand would have been used in furbishing or altering them.
There is still the question of the actual bore of this barrel, which would seem to add a bit more perspective in this analysis.
Thanks very much guys.
All best regards,
Jim