Starck made a lot of button mount sets. They're not hard to spot with very straight lines and generally low-quality nickel. The stocks are flared at the bottom and, of course, the beading and combing is very deep. On some of the sets, they left a small raised bead of ABW just above or beneath the ferrule. The ferrules were all secured to the wood with the scoring on the inside, as seen on Starck's home page.

The sound and behavior of Starck bagpipes is very good, if not slightly underrated.
This Starck bagpipe (below) has just about everything. We see some really interesting detail just under the button mount. We also see the raised ABW bead facing the ferrule. One of the button mounts is very red, which caused me to look closer. The set, or some of the set, may be made of cocuswood. We see some sapwood showing on the middle tenor bottom, which looks like ABW. Rings are ivory and the bushings are ABW. Of course, the beading and combing throughout is just awesome.
This metal valve is interesting. I found it in an early Starck bagpipe that I restored. Made of brass with a small hard rubber ball within the basket.
Starck - Button Mount