Just take a 224 barrel drop, chuck it up, stick out enough for you to turndown to fit snugly into the RCBS spin tube, 3/8 to half long to the shoulder. Turn down the leftover towards the chuck to the desired OD. Part the piece to the desired length.
Chuck the parted piece into the chuck and face off the parted end to dress it.
Chuck the parted piece into the chuck and face off the parted end to dress it.