"World Part" in Bb Bass?

[Timswisstuba]

The easiest way to deal with Bb bass clef is to take a BBb tuba and use CC tuba fingerings.

Occasionaly I am handed a folder of music with a mixed transpositions and I am expected to play it at sight. If I couldn't do it or complained, I wouldn't be asked back.

In the end, it doesn't matter what label we use for a pitch. (do, C, ré, Bb, Si bémol, H, Es etc..)
What comes out of the Horn is more important than what we see on the page.