Suggestions requested. I've been playing a Bossey & Hawkes Imperial cornet with a Reynolds B mouthpiece for over 25 years. I managed a full range (with the occasional E and F above the stave)with a half decent tone but the third valve caused me all sorts of problems. I decided to treat myself and bought a Besson Soveriegn. The mouthpiece that came with it was an Alliance 3B. I 've had the instrument 4 months now and even though the tone produced is much better (colleagues say it's a bigger bore) I am still finding it difficult to play up in the top register - even top C is difficult after about an hours playing. I'm putting in the practice and have marginally improved by using a Dennis Wick 5. My old Reynolds mouthpiece doesn't really fit into the Sovereign. Following threads in TMP most players say that the mouthpiece isn't really relevant - breathing and support are. My deduction therefore is that my problems stem from the larger bore - it's also a longer instrument so I have to hold it farther away from my body. Anyone out there got any suggestions? Could my practice sessions incorporate something to help? Sorry, turned into a longer question that I thought. Shipbuilder.