With Dillon dies, you have to use a test gauge to set the sizer correctly, and use it on a finish shell as well, to make sure that the case was trimmed correctly (not sticking out the front of the gauge), and that you did not over bullet crimp to budge the cause shoulder and case will not longer gauge correctly as well.


As for match chamber barrels and leades, need to figure out what the zero jump to lands with the bullet in play/in the barrel in play to begin with, and with a progressive machine, or some single stage machines that will have variance is bullet seating depth as well, have to add in  .006" of seating distance so you not getting embedding of bullet to lands at loading.
Note, where are ways to get a progressive press to hold tighter variance on bullet seating, but it involves add in shell plate supports that will hold it trammed as the die is seating the bullet.

Even with a press like the foster co-ax that can keep the seating depth down to  under.001" variances, and with a bullet type that is very consistent as well, still want to dial in an .003" distance of jump, since unless the case necks have been unified turned, it may be adding in a variance of .001" to the mix on seating depths.  

As for bullet tail bullets, up to .008" of jump to lands will not cause a problem.

And I bring up bullet types, since have picked up match bullets that where classified at seconds (differ batches through different machines.yet in the same 1K count box), and when the bullet were ogive mic's to see how uniform they where, all over the map, with some .003 ogives touch point to base distances.

Next one, double check the ogive seating guide on the die!!!!
So are just a nightmare to begin with that will never seat two bullets the same to begin with.


On a set of match dies, will take the time to use the bullet type in play, to clean up and  lap the Ogive groove to the bullet type in play, so the bullet seater will consistently seat under the .0005" variance range.


So to sum up, just because you think that you are seating the bullet for .003" of jump to lands with the round you are using for testing, does not mean that the rest of the bullets are seating the same for the entire batch.  From bullet seating steam, neck case differences in thicknesses, the press in play, and even bullet crimp if you are using any, some bad combo's may cause variances is seating depths up to .009" or more, even when you have bullets that are very uniform to begin with.


As for back to Dillon die's, should be already faced short enough with a Dillon shell holder, that should have a gap between it and the shell plate when it sizes the case correctly via the case gauge.  That is is you are running a full boat in the shell plate as you set it to help stabilize the shell plate with pressure on all sides to start with.  If Dillon dies and non Dillon machine, may have to face the sizer to get it to size correctly for that set up isntead (.010" off the face of the sizer).

To add, what the leade is on one match barrel, may not be the same leade on another match barrel even from the same barrel manufacturer.

You have to come up with the Zero jump to lead distances for that barrel/with the bullet type you are using as your base line to start with, then dial in at least .003" jump to lands on a very good set up, .006" jump to lands on a iffy set up, and .009" jump to lands on a set up that will only hold the .006" distances on a good day at most.


And no, have not even touched on how concentric the set up is seating the bullet in the case to start with, that you are basing the zero jump to lands to base measurement to start with.

https://www.accurateshooter.com/gear-reviews/new-wheel-drive-concentricity-gauge/