A howdunit with a twist

I usually have a pretty good idea of how antique pens and pencils were made, but every now and then something turns up that provides a real puzzle. This American-made sterling silver dip pen is the latest: it is made with a very deep twist pattern, the construction being, as usual, hollow within, and with the nib-holding ferrule a separate component soldered in place.

There are no visible seams in the twisted portion, which has clearly started out as silver sheet. It is not cast, and if it was die-stamped, the halves have been joined with extreme skill. My initial thought was that this pen might be related to a group of Gorham-made silver dip pens, in which a twist pattern appears to have been applied with some sort of die to a one-piece pen blank, without any joining. The Gorham pens, however, have a much slower rate of twist, and usually just a few impressed flutes to the pattern. They are also all fully Gorham-marked, whereas the pen shown above is marked rather differently. In any event, figuring out how the Gorham pens were done is on my long-term to-do list -- long-term, since it's likely that the process was a trade secret and never patented, and since the Gorham archives at Brown University aren't going to be accessible for a while during renovation of their home at the John Hay Library (not that they are easily searchable, especially for such a narrow and esoteric question).

UPDATE: It appears the pen was made by wrapping a channeled strip around a mandrel; the seam runs helically. Discussion here.