Major runout with 280AI my thoughts?

[elmerdeer]

Hi guys I have a tried 3 280ai comp seaters 2 reddings and a forster reamed out.
So my problem is no matter what die I use to seat the bergers 168gr on Nosler brass I get 005-010" runout. My brass is sized and only has 001-002" runout max, it is annealed every 2nd firing. Its sized with Lee collet die and or redding full length die.
Now I do not believe its my presses forster coax and supreme rockchucker,I'm pretty sure dont have donuts causing that amount of runout.
It happens only with my 280AI seater with nosler brass, I use same setups with my 7mm Dakota, and my 7rem mag and the most I get is 003"runout.
So Are the necks of the nosler brass bending somewhat during the seating process? As that seems to be the only thing that makes sense to me .
Anybody ever run into this particular problem??

Thx
Elmer

 

[FearNoWind]

Can't be sure what's causing your runout, Elmer, but if you haven't tried it yet try starting the bullet into the case with the slightest amount of pressure then rotate the case 180 degrees and finish seating the bullet. That has made a lot of difference for some of my runout issues.

 

[scottishkat]

Do you rotate the case part way through the seating process. If not try that and see if it helps. Also had a person at redding recommend I not use a lock ring and that helping with runout. I check my brass for run out after each phase and find the results surprising to say the least.

I started rotating the case during the seating process quite some time ago and it has helped to minimize runout. Seat the bullet about 1/2 way then rotate 90 degrees you can do it more than once each time if you wish.

I use all redding dies and have several competition die sets and there quality is good. They're not without their issues though I purchased a body die in a set for my 6.5x284 and marked for said and actually sized brass for 6mmx284. They replaced it but my brass got worked more than needed.

Good luck and shoot straight.

Bob

 

[Ridgerunner665]

Are you using a VLD seating stem in the die? Don't know about the Forester, but it has to be bought separate for the Redding die.

 

[elmerdeer]

Answer to your questions. Yes I have tried rotating the case, I have tried leaving the die loose not locked, I have the vld stems. I cant think of any other reason that this is happening other than the necks bending somewhat even though it sounds weird??

Elmer

 

[dig]

Use a rubber O ring under your seating stem. It will help float the seater. Also rotate 90 degrees each time. That should help.

 

[frankinaustin]

two questions for the group:

1.) Why would NOT using a lock ring on the seating die help with run-out? Is this because not using a lock ring helping the axis of the seating die be more perfectly in line with the axis of the press ram? (i may have answered my own question, but would love to hear from you all)

2.) specific question on "using a rubber o-ring under the seater" - any chance you could load a pic of what you are saying? That is interesting and I'd like to see that in action.

 

[No Problem]

Is there any chance that you are sizing there neck to tight and when you push the bullets in they go a little crooked or the neck may bend. May be you could try running a expander on a die and seat a couple bullets to see if it helps.

 

[Canadian Bushman]

First things first, you need to narrow down the part of your process that is causing the runout.

Probably gonna be either sizing down, expanding, or seating.

A few things to consider

When you check a neck, then press a bullet in and check the bullet your projecting the tolerance away from the datum, or the point the case is supported.
If the neck measures .002 and the ogive of the bullet measures .006 it may have been there before you seated the bullet.

Your brass should be near perfect when extracted from the chamber as long as you extract them softly. Dont rip back on that bolt and bash the neck into something or you have no baseline.

Bad brass with uneven thickness will always run out, nothing you can do will fix this.