Do not know the best way but when going to the trouble make a transfer with the bullet that is to be used.

I drill the flash hole on as many cases 10 cases to save time time the next time. I drill the hole to a diameter that will allow me to insert a small wood dowel or a cleaning rod, the rod is to be used to push the bullet out of the case once the test case and bullet is in the chamber.

with the case with the drilled out flash hole/primer pocket, seat a bullet, the seating depth is not an issue.

Remove the bolt and then chamber the test case, insert a dowel, push the bullet out, when it stops it is against the lands (as a side note I have pushed bullets out of the case before the bullet hit the lands).

Remove the test case and use it as a transfer, raise the seating die in the press and loosen the nut on the seater plug stem and raise the seater plug stem to assure it will not make contact before the set-up is complete. Place the case in the shell holder, raise the rap and then lower the seater die until it contacts (just touches) the mouth of the case, raise the die 1/4 turn (.017 thousands) and secure the die to the press with the locking nut, lower the seater plug/stem until it contacts the bullet then secure the seater stem to the die with the lock nut and lower the ram , remove test case.

When using this technique the die will be set up to seat bullets for your chamber with ZERO thousands off the lands less head space.

With a height gage or a dial caliper the height of the seater stem can be measured for a reference and indexed to .000 (zero), when changing the 'off the lands" with accuracy less head space.

Head space is not included in this measurement because the case is pushed forward with the shoulder of the case against the shoulder of the chamber.

Other choose to shred the mouth of the case to make it easy, I like the bullet hold (neck tension) of the unshredded case mouth.

F. Guffey