Re: Neck Bushing and Body Dies or FL Bushing Die???
Custom benchrest dies are very expensive, and you'll get pretty near the same result by using a bushing type FL die (controlling neck tension) and using an accurate method of measuring your chamber clearance (at the shoulder).
Unless you're shooting a $5,000. benchrest rifle in formal competition, setting the height of your FL die "accurately" is usually the best way to go.