Western Bit types - how do they work?

I have done a quick search but can't find anything to explain what I need explained - What does each type of western bit do?

I recently bought a young reiner and I have continued using his previous bit, but need to buy my own for him. His bit at the moment has 7inch shanks and a port with a barrel.

I don't want a 'harsh' bit but I have no idea what to use or if I should get the same as what I use now (which works fine, but I don't know if it is a harsh type?).

I want to know what bits are softer or harsher
How do the different size shanks work? Shorter vs longer?
And the port, you can get them 'rectangle' with a barrel or you can get the curved etc... how do they work differently?

I will ask my trainer but won't see him for a few weeks so I wanted to get my research in

Thanks in advance!!

Fortunately we have an awesome member on here who made an excellent thread for this.

Bit Information (Curb and Western type bits and hackamores)

I personally really adore the Billy Allen bits myself.

Billy Allen Bits

My reiner goes in the first bit on that page.

My Own Informative Bits and Bitting Thread

That was very helpful!
And I didn't measure the shanks properly, they are closer to 5 inches I reckon.

Now I guess I need to decide if the same type is the way to go or if I should change it maybe to something slightly softer. He seems happy with the current bit though.

If he seems happy with it and goes well, I don't see a reason to change.