Basically you want to play your GG contra in a concert/marching band setting right? I had actually written a fingering chart for that purpose. The only problem is anything above the concert Bb in the staff starts getting really squirrley and hard to tune. I think I actually tried playing one random high note with all fingering combinations and it read the same on my tuner. However, if you want to take the time, its best to have a tuner and go from there. The horn is in the key of G, which means that the tuning concert pitch that comes out of the horn is a "G." That is the same G played 12 on a BBb tuba. If you follow the chromatics up from there, you will see the BBb, fingered open on a BBb tuba, is actually 23 on a contra. please PM me for any other questions, I'll try to find that fingering chart i wrote. I wrote it because I find it sad that these huge majestic instruments are considered useless and obsolete. Also, im sure they will turn up on ebay as "marching tuba" and I can see some kid buying one not having a clue how to play it.