I ditched the expander ball years ago and my concentricity improved immediately. You can use the Lee collet die or pick up a mandrel body like this one...
https://www.sinclairintl.com/reload...s-prod38807.aspx?sid=63474&pid=36422Then just buy mandrels for your calibers. I use the "turning" mandrels which are cut to .002 inches below caliber diameter. "Expander" mandrels will get you .001 inches below caliber diameter. They're made in steel or carbide. Carbide supposedly doesn't require lube but is significantly more expensive over the steel variants.
Carbide turning mandrels....
https://www.sinclairintl.com/aspx/search/productdetail.aspx?sid=63474&pid=36422Steel turning mandrels...
https://www.sinclairintl.com/reload...s-prod33136.aspx?sid=63474&pid=36422