One thing you need to look for is that there is a built in error in the Hornady tool because of the size of the modified case. The modified case is inserted into the chamber until the shoulder comes in contact with the shoulder of chamber. At that time, the case head will not be at the same location as a loaded case that is held against the chamber shoulder (if you PFLR or neck size) by the bolt head. Essentially the headspace measurement or the shoulder gap in a belted case.
I have 3 ways to measure distance to the lands; the Hornady, the Sinclair and a tool I call the Reeves tool, shown here with the Hornady
Essentially it is a commercially manufactured stainless rod with 2 locking collets, you insert it in the muzzle to the bolt face and lock the rear collet
Insert your bullet to the lands with the Hornady tool and insert the rod to the bullet tip and lock the front collet
and measure between the collets
no built in error and fool proof (which helps me out).
Then use that same bullet to seat in the first load and measure with the comparator to the ogive for seating the rest. The only variable is how much pressure used to seat the bullet against the lands.