The clarinet is one of the least flexible instruments to tune because of the fixed length of the barrel. It is often colder in our auditorium, or outdoors, than it is in our band room. In colder temperatures, instruments tend to play flat. There is usually little or no room to push the clarinet barrel closer to the upper joint, in order to bring up the pitch.
Players are now able to tune, as they play, without the use of tuning rings or additional barrels.
The design, not the weight, is the primary factor in establishing sound quality. To facilitate movement, hold the clarinet on the upper joint just below the barrel, reach up and cover both wheels with the pad of your thumb and press in while pushing up or down. You can also use your free hand to gently pull up or push down the barrel as you press the wheel.