Neck turning will give you more consistent neck tension only if you use bushing dies, using bushing dies without neck turning defeats the object of bushing dies because of variations in neck wall thickness, with unturned cases standard dies with a sizing button will give more consistent neck tension then bushing dies. If you get a donut form, KM neck turner mandrels are available with a built in donut cutter. Neck reaming will not remove case neck thickness variations, it is really only used when necking down cases to smaller calibres and then combined with neck turning

TB.