Sorry if it seemed like I was saying Ludwig made the metal shells. That wasn't my intention. Just to say that the shells were made in the USA and perhaps in North Carolina.
I'm not sure of the best way to answer you so I'll try two ways.
Simple answer: Ludwig outsources the shells to a different company in the USA.
Longer answer: I believe there was a misinterpretation of this sentence of mine:
I believe they manufacture Black Beauty, Supraphonic, and similar shells...but not the "import" metal shells.
and Vintagemore2000 read "they" as "Ludwig". But if you look at the previous sentence:
I remember coming across a picture of a factory in the vicinity of Ludwig which makes the metal shells.
and what followed:
Alas, I didn't store the factory name away. ... Hopefully somebody else remembers the name of the factory or has a link to the picture.
The "they" was intended to mean the other metal working factory to which the shells were outsourced. I usually try and avoid "detached" pronouns and the like so that this sort of thing is less likely to happen. But I didn't avoid that construction in this case. I am sorry, because I didn't avoid the ambiguous construction.
I'm starting to feel I'm flogging a dead horse here. Have I answered your question well enough? If not I can always try again.