Lovevixen555, I guess you measure differently than I do. I can't even find 2 different model Bach trumpets that measure to within .001 of one another. I hate to burst the bubble, but most leadpipe design IS trial and error. All of the numbers including bore size are meaningless when trying to predict behaviour. The only thing an OVERALL larger bore has is slightly more volume of air in the horn. It says nothing about blow or sound. When players are told that they need large bore instruments, they look for them. If the expectation is that a large bore trumpet has a dark sound, then the other parameters are adjusted to get that. The awake player knows that there are large bore screamers and medium bore dark sounding horns - they just don't talk about it as the immature get on their case. There is also no "ideal comprimise". 90% of the players don't have the chops to really experience the difference, so perception is more important than specifications. The myth of the perfect horn for the way one plays assumes that that person has enough consistency to match the inert piece of brass. The truth is that most players chops are all over the place, as well as not even really knowing how they sound to the audience. Hardware is NEVER the answer. The sooner that message hits home, the sooner the player will do what is necessary!