Are there proofs unlisted in Krause?

I know there are some. I don't have my books up here. If no one answers before tomorrow, I'll let you know. Do you want a list of them all, or do you have something specific in mind?

Hamburg schilling 1855A.

The coin is listed in Krause, but I see no mention of a proof.

I can't find any Hamburg Schilling proofs anywhere.

Billon coin (.375 Silver) in Proof? I don't think so! At this title they must add some Nickel in the alloy for stopping the copper to erupt to the surface of the coin (technology used in 1930's for making the .500 silver coins to look like .825).
As I know, the Nickel wasn't used in 1855 in coins alloy.

Proof Hamburg schilling 1855A? I greatly doubt it.

Okay. I saw one, and the surfaces looked somewhat better than usual, though there were some marks. (bagmarks?)

It's possible. Krause can't possibly list everything and when I checked Krause some time ago about my 1834 Alexandrine Ruble, they didn't mention about PROOF. It was then quite recently that there were indeed proof types of such. It maybe possible that yours can be a proof... do show us a picture

Luebeck, 5 Mark
There are also known proof pieces from 1908, 1913