The Precision chart you have is most likely for gripped clubs. However, we recommend no grip when checking the frequency progression for a set. The old chart was meant for use with the old Precision machine. Depending on the grip you can get different readings. An oversize grip will give a different reading than a standard size. A cord grip with a firm feel will give a different reading than an softer grip. The old Precision machine actually had two marks on it for a different clamping dimension to use depending on what type of grip you had.
No grip simply is a more consistent and comparable way to do it.