I recently reformed some .243 cases to .22-250 cases. I had to turn the necks, but that was because after reforming, trimming and annealing the new necks were the old shoulder material. The shoulder brass being thicker I had to turn off about 3 to 4 thousandths. You shouldn't need to turn yours though since you are shortening the cases and expanding the necks. Neck thickness should be about .013.