BlueSwordM
(BlueSwordM)
14
@DB Custom, the Fasttech Carobronze they are made of phosphor bronze rather than Beryllium Copper.
You can get unplated Beryllium Copper springs, like in this picture, but it is not recommended because of heightened contact resistance which can go even higher than non-plated steel when oxidized:

Most copper alloys used in springs aren’t corrosion resistance because they are used for current handling, and using one would either affect conductivity/contact resistance/yield strength.
Also, with higher currents come higher temperatures, and higher tendencies to oxidize.
I can already see it on his sample, the bottom wire being already oxidized, and the top coil starting to be so.