Just checked Track for you - no .620". I think I'd jsut bite the bullet and order a .625" mould from Jeff. The ball should run .621" to .622". That should work just fine. You could talk to him and tell him you want the ball to come out at XXX" and that you'll be using XX alloy. He may have some suggestions. If you ordered a .623" mould, it might be about perfect at .620". I don't know if he does this fine a measurement. The .725" mould I have from him, casts .722" in WW metal and .720" in Pure lead.