That Redding tool looks impressive. I use the Stoney Point (now Hornady) comparator setup, as it allows me to determine shoulder setback, and ogive-to-rifling distances, when I don't soft seat my bullets. Aside from being relatively inexpensive, if I use 2 of the inserts for bullets, I can measure from the boat tail to the ogive and further refine my bullet selection. --You might be surprised how much bullets from the same box will vary in this dimension, which closely approximates a measurement of the portion of the bullet in contact with the bore.