Hello, I was asked a question by a prominent player today concerning Bach backbores and his lack of knowledge of the Bach backbore numbering system. He is new to the â€œthreadedâ€ backbore concept and has always played the backbore that the Bach factory suggested and had sent with the rim/cup of his choice. I have my opinions on the subject, but I told him I would ask my esteemed colleges on the TM site to either validate or â€œtear apart â€œmy long held concepts. He told me he went to the Selmer site and said " Well, a # 24 comes with an A cup, which is described as bigger (than what?), darker (than what?) symphonic and a V cup comes with a # 25 which also list " big " as a description along with a 87 ( big, free blowing ) so what gives" Simply list biggest to smallest: 24 7 3 117 87 76 41 57 25 Plus any others not listed. If you can give a personal description after the backbore number, so much the better and I will forward every and all determinations to him. He asked I didnâ€™t reveal his name, but itâ€™s an older â€œhousehold one â€œand you would be surprise how little some top named players know about the gear they use. Larry Note to Bach Trumpet Moderators; I asked this question in the â€œ Bach Trumpet â€œ forum because I hope it would get more viewings and more diverse opinions then in the â€œ All - Encompassing â€œ mouthpiece forum, but if you feel it belongs in the mouthpiece section , Iâ€™ll understand if it gets moved.