Franz, the way I understand it is the gap can be helpful with response and maybe slotting or hitting the note without chipping.
Yes, I understand how it is in theory but, as I was able to experiment in my case, on my Prestige where the step between leadpipe and receiver is minimal, the effects of the more or less marked gap are minimal or zero ( at least for me). My question is whether there is more pronounced step between leadpipe and receiver on Adans and therefore it is justifiable to have a gap regulator.
2007 Besson Prestige 2052, 3D+ K&G mouthpiece; JP373 baritone, 4B modified K&G mouthpiece; Bach 42GO trombone, T4C K&G mouthpiece; 1973 Besson New Standard 3 compensated valves, 3D+ K&G modified mouthpiece; Wessex French C tuba, 3D+ K&G modified mouthpiece.