I see .462 and .459 all across the board when looking at trumpets when its talkign about the bore size. What exactly does this affect and how does it affect the sound of the trumpet. Plus what is considered a large bore size and a small bore size?

i think it crosses from "medium large" to "large" at .459. The bigger the bore the more air you can push through it, and the mellower the tone. I have a .464 and I love the big bore. I remember trying out other peoples smaller bore trumpets in high school and you really had to push with your diaphram to get the notes to come out, but with the large bore the horn seems to do that work for you. An example is I think Maynard Ferguson plays (or at least used to) a .474 (which is huge!).

What exactly is the bore on my trumpet?

Depends on the model you have, Phil. What do you have?

Bach runs large. Their large bore is something like a .464, medium large .462 medium .460 small .459

Most others run somewhere in around that.

Yeah I play a .459 bore Yamaha Xeno, and I`d disagree that small bores are hard to play. I would say the exact opposite, that small bores do all the work, and large bores are more difficult to play with flexibility on.

It all depends on the player. I can play up to a double high C on my horn, and I can play up to a double high C on a .474 maynard ferguson Holton. It just sounds different, and is easier to do on a large bore horn. (In my opinion).

What kind of playing do you do? If you need to play techinically difficult passages, at great speed all the time, go with a small bore simply becuase they have more resistance and respond better.

Want to blast away at lead trumpet, gun out the extreme register at extreme volumes, go with a large bore horn.

I personally use a huge, heavy monette mouthpiece on a small bore horn to do classical and solo work. But, I use a GR technologies lead trumpet mouthpiece to play lead trumpet. I still use the same horn, But I think I`m going to soon purchase an extra large bore Xeno to play lead trumpet.

It all depends on what you are playing.