In addition to a Callet Jazz trumpet which is just OK, I am attempting to play a Holton Committee Elkhart with a Bach 3-c mouthpiece I love the full sound of the cornet and an willing to accept the apparent 2-3 note reduced upper register but I have to keep the tuning slide tight in to get close to being in tume. I feel I am bending the notes sharp to stay in tume and so do not get the full winderful tone the insrament is able to produce when I "exercise" it. In other words I seem to play flat with the cornet compared to when I play the a Bach 3-c mouthpiece on my trumpet. I had the same problem with the King super so I traded it in. I love having the different sound of the cornet vs. the trumpet but to get it to be in tune I seem to have to not allow the fill wonderful centered sound of the instrument out. What am I doing wrong?