Most trumpet players who first experiment on the shallow mouthpieces find that their upper lip touches the bottom of the cup. Many of these immediately declare the mouthpiece unusable. Or soon after playing one on a gig declare "I can't play shallow mouthpieces because I bottom out". To which I compare to the person whom upon first driving a powerful foreign sports car complains that the ride is rough, car is low to the ground and that they just barely touch the gas pedal to find that the car is going 80 mph. Or maybe if its a really powerful car they feel uncomfortable with the noise of the turbo charger and exhaust system. It goes with the package. So YES! You do tend to bottom out on the shallow mouthpieces! This where you can derive the POWER in the upper register! Why would this bottoming out be desirable? Well to explain if we examine some of the upper register technical studies we find a few, like Louis Maggio and Claude Gordon systems actually directing the student to place more upper lip within the mouthpiece. And/or pucker. The "Maggio Monkey" Featured here: http://abel.hive.no/trumpet/maggio/cover.jpg Was used as a reference on how to pucker forward. By pooching more upper lip into the mouthpiece the student often found his upper register attainable. And then again some trumpet students couldn't play this way. But coupled with the emphasis upon pedal tones and the Maggio Monkey a lot of trumpet players developed a strong upper register. In fact this was how I initially got my first solid High G's and stuff. At least when i was first learning high notes. Now I don't pucker all that much having refined the movements. But the pucker was a catalyst for my early high notes. OK so what does this pucker do? Intentionally "bottoms out" your chops to the floor of the mouthpiece cup! Bottoming out in a fashion very similar to to what the average trumpet player finds when he blows into a shallow screamer piece. I just remembered from my early days on the Maggio method. All I had were deep Bach mouthpieces at home but when I went to school I could borrow my buddies shallow screamer pieces. So with using the Maggio to pucker deep into my large cupped mouthpieces and THEN switching over to a "bent dime" I found myself able to slur perfect two octave glissandos up to and above the High G. My band mates were impressed because the tone smeared perfectly up the scale. Not revealing any audible partials. The shallow pieces can help the trumpet player "leverage" their upper lip as it lightly engages the side and floor of the mouthpiece cup. Taken to excess it is a problem because the air can't pass well through the puckered mass of useless flesh plugging up the works. But stopping short of this extreme the chops can gain an enormous advantage when playing the upper register. Conversely some cats truly can't blow shallow pieces at all. Example: A friend of mine is a strong amateur lead trumpet player. He can squeal some decent sounding Double C's. Meanwhile the dude can also ride the High C area for a long time without getting tired. If there's a weakness to his playing it is that he doesn't get that big of a sound. Other than that though he's good enough. So I looked at his mouthpiece. Although the inner rim diameter was medium to slightly small the cup depth was near French Horn mouthpiece deep! Odd huh? Well maybe not. This "squeak artist" gains his advantage to the upper register through means other than bottoming out. My theory is that because he plays with a forward jaw his chops gain register from the leverage achieved as the upper lip gets sandwiched between his lower lip and teeth. Difficult to describe in words but that's how his "trick" works. Whether he knows it or not that is. Conclusion: What practical results can you possibly get from shallow pieces? Well if you've previously had trouble with "bottoming out" on the shallow pieces do not necessarily denounce them unplayable. Not immediately anyway. Practice these pieces in the middle and lower register up to the point where fatigue sets in and "bottoming out" occurs. That's right: fatigue can induce bottoming out. So first build up your middle register endurance on the shallow ones before declaring them unplayable. I've been playing some extremely shallow pieces for many years and can blow them through various stages of fatigue. From being freshly warmed up at my peak of performance to near totally burned out at the end of the third set. All without bottoming out excessively. But it took a while to get there. And again it is also possible that the shallow pieces aren't for you at all. Like I said certain players have physical advantages that can only be utilized on the deeper cups.