Do ALL operations and actions exactly the same.
Size concentrically 180 deg.
Weigh bullets/sort.
Weigh brass/sort.
Weigh each powder charge TO the tenth.
Measure exactly.
Seat concentrically 90, 120 or 180 degrees.
Minimize runout.
If using a crimp, crimp concentrically 180 degrees.
If shooting copper, allow copper equilibrium...don't remove copper overcleaning.
Cold bore shot(s).
Wind management.
Use multiple strings if necessary.
