Oustanding, Alexander!
It certainly is a rather small caliber arquebus barrel (probably 12-15 mm), most probably hexagonal (characteristic of that period), and the overall length should be ca. 80 cm.
The image from Diebold Schilling's
Berne Chronicle you seclected conveys a perfect idea of what the arquebus might have looked like, and why the barrel loops make sense.
What I am hoping moreover is that your 'good man'
also has photos of the smaller (most probably bronze) arquebus barrel of ca. 1490-1510 that can be seen in the upper right corner, above our barrel in discussion.
Thank you so much
and best as always,
Michael