Michael, I should clear up the misspelling:
I have to admit that was astonished to see the term of a the Late Gothic ornament quatrefoil misspelled as quatrafoil by a musem staff member ...
The video that came from was produced and directed by me, my company is Springfield Arsenal LLC. Perhaps you were thinking of the US National Park facility in Springfield, MA, known as "Springfield Arsenal," an historic site. We have nothing to do with that, we are a small company dealing in military relics, with a sizeable collection of artillery and odd items on the side.
Of course now you must recognize that the misspelling was inserted on purpose to attract the attention of, and elicit comments from highly educated and knowledgeable persons such as yourself!
I will make it a point to make larger images of the hackbut barrel available, forgive me but I will probably continue to use the term hackbut out of habit even though it is obviously a barrel.
I have asked some local experts in Altdeutsch here in the US to assist with a competent translation of about a paragraph of material on Ulrich von Schellenberg, from the online version of the ADB. The text is in what I'm told is "very old German." Google translate cannot make sense out of much of it. I had years of German in school but that was centuries ago, or so it seems, and most of it is gone, and I cannot make sense regarding who is doing what to whom in some cases. Friends who are native German-speakers cannot read it. There may also be some errors in it, or it could simply be my mis-reading. One portion of it mentions "when Ulrich was just beginning his military career in 1501.." That does not make sense to me because since he was born in 1487, he would have been only 14 years of age in 1501, at which time I suspect he had not yet left home to attend law school in Italy.
We have two other odd early weapons and will certainly undertake discussion of those here after we get the basic information on this hackbut digested.