Ok I have seen people convert Cornets into trumpet before. I am also aware that Conn had some models a long time ago that where cornet's that had trumpet leadpipes and main tuneing slide. So I have a few questions???? First if you take a cornet and convert it to a trumpet leadpipe and tuneing slide is it still a Cornet or has it become a trumpet by default? Second if you convert one to a trumpet do you have to change the bell as well to make it technicaly a trumpet? third what is the length difference between a cornet's leadpipe and a trumpets leadpipe and how much of the 2/3 conical tubeing does the leadpipe make up? I know that was a bunch of questions??? that did not even touch though on the shorter shank length of the cornet mouthpiece or the if the tuning slides are useing conical or not etc.... I am guessing ht eslides are not because when I have seen them turned into trumpets the slides for the valves where never changed and only about 1/2 the time was the bell changed. It was almost always just about the trumpet leadpipe and makeing or finding a tuneing slide that allowed everything to line up properly and adding on some length tot he knuckle comeing out of the third valve to mate up with the now trumpet leadpipe and tuneing slide combo.