A Gewiss coloured one is up for sale in Italy. The seller has used some of my text which I have pointed out to him.

bianchi proto 1990 columbus MAX campagnolo c record collectible | eBay

The serial looks like BCOC 360 but it is not clear. My list already includes that number from another bike and I have a picture of that frame - in which it looks like it has been repainted. Either I have read that one wrong or the one in the auction.

I have added some serials to the list from earlier input above:

F030
F041 (added 2017 10 13 owned by c c rider)
F058
F136 (added 7/7 2016 found at "vintage art work" on flickr)
F208 (added 2017 10 13 - owner - bloodytea.
F.243 (added 5/5 2016 - and also has a dot as 254)
F.254 (has a dot between F and number)
F287 (added 16/8 2016 -found in old ebay auction)
F326 (added 17/1 2017 - found at registrostoricocicli.com)
F370
F382 (mine)
F403 the one in the PDF-file at http://www.ciclimasini.com/images/90...i%20Caurus.pdf

BCOC104 (added 25/10 2016 courtesy of scooterpants) Stolen in 1993 - if you see it - let scooterpants know.
BCOC112 (added 25/10 2016 courtesy of scooterpants)
BCOC115 (added 25/10 2016 courtesy of scooterpants)
BCOC157
BCOC359 (last digit might also be a 3) (added 28/2 2017 - from telaio Bianchi Columbus Max | BDC-Forum.it)
BCOC360
BCOC515 (the O probably stamped at an angle - making it look like BCCC)