Okay, Jose... I don't shoot competition but,

[wesseler]

Just got a Sinclair concentricity guage and want to know how to reduce runout from my standard Redding FL and seater dies.  I tested the bullet runout on 15 .223 rounds.  .000 runout:1 round;  .001 runout:2 rounds; .002:7; .003:1; .004:2; .005:1; and one with a runout of .007.  Probably not too bad for standard dies.  It will be interesting to put the five rounds with the least runout and five rounds with the most runout on paper and compare the difference.

[Jose Grande]

You can effect runout by half-way seating a bullet, lowering the ram, & turning the cartridge half-way around,then finish seating. That should give you less runout.

Post again & let me know if this works for you.

Thanks for a great post by the way. Not many worry about runout. I'm one of the few that do.

[Bob_K]

Your test could be enlighting.  You also might try marking the high side of any ammo that has runout and loading that highside oriented in the chamber inline with one of the locking lugs.  You can get surprisingly small groups.

When I was shooting service rifle LEG matches, I would measure the runout of the ammo that was issued to us and separate it into batches.  The most runout batch was used at 200 yards off hand.  The next worst runout group was used at 200 yards sitting.  The best batch was used at 300 yards rapidfire.  The second best runout was used at 600 yards, orienting the highside against a locking lug.  Runout on the issue ammo was thought to be because of a thicker neck at that part of the brass.