Re: R C B S competition dies
I'd keep the seating die you use now and get an RCBS or Redding full length bushing die. Use a bushing that's 2 or 3 thousandths smaller than a loaded round's neck diameter. Maybe get extra bushings if you use different lots of brass with different neck wall thickness.
Use a separate die to deprime your fired cases, then clean them before lubing and sizing them in the full bushing die.