Welcome.
I hope you get a lot of responses.....and I can just about guarantee you most of them will be different.....LOL
I am not a professional, but I have been turning calls for over a decade. In that time, I still can't get one of my inserts to sound as good as a purchased insert.....so I wont even begin to offer my opinions on that end of the process.....
As far as the barrels go ;
You will need a 5/8" expanding mandrel. I have used jam chucks, Hut's "expanding rubber" ring system on a pen mandrel......nothing beats an expanding 5/8" mandrel.
One other suggestion from me.....spend the money and buy carbide tipped turning tools. You wont regret spending the money...