I have sized down .003 but try to cast closer to the size I need.
I have molds from Veral Smith, NEI and Paul Jones that drop bullets I shoot as cast they drop bullets to the size I specd with my alloy, I usually go .001 over bore size.
They cost alittle more than RCBS, Lyman or Saeco but cast very round bullets of the correct size, although they still need lubed and unless you pan lube them you will still need a lube sizer and sizing die.
I use RCBS, Lyman and a old Magma/Star lubsizer that you just push the bullets straight through but it doesn't work that well for gas checks, but is much faster for large quantities of bullets.
