One of my customers tried this a couple of years back, when .204 cases were darn near impossible to find, and had problems with the necks being too thick. He didn't want to spring for the tooling to turn necks. I don't recall any other issues, though. The squeeze from .224 to .204 isn't real severe. He had Redding dies and used the seater die, minus the seating stem, as in intermediary neck die before running them through the full length die.