What trombone mouthpiece is best for use with a king 360 b trombone?

Answer 1

Mouthpieces are better matched to the player, not the horn.

For example, a beginning or young player--typically a student--would use a size 12C mouthpiece. This is the size that comes with most student horns. The mouthpiece has a shallow cup and offers a bit of resistance. This is fine for young students who have yet to develop their lungs and technique.

More experienced players choose mouthpieces with deeper cups and different rims that allow more air to pass through. They have developed the control necessary to play loud or soft and the larger mouthpiece gives them that control. A typical size for a symphony trombonist is a 6½A (or 6½AL).

A bass trombonist might choose a 1½G which provides a large, deep cup and a larger bore for more air to pass through.