concentricity problems

[cgordon]

Loading for the 28 nosler and with new brass and the 195's concentricity of the brass and loaded rounds were perfect i checked every one of them and were .002 .001. after i fire formed by brass bumped the shoulders back .002 and cleaned them and got ready to load some more. i checked my brass and they were all under .001 concentricity using my widden full lenght size die. pretty happy at this point i charge some cases and seat a 195 in the widden comp seating dies and they come out at .007. I try some more and get the same results. nothing has changed with my dies. i tried my other seating stem that came with the die set and its the same change shell holders thinking maybe something was wrong with it, same results. i'm not sure why they seated so good in new brass and not so well in the fire formed brass. the initial neck tension on the new brass was .0025 and i wanted to try .0015 on the fire formed so i changed the neck collar.

 

[Barrelnut]

Are the neck mouths square after fire forming? Did you trim and square them?

 

[dok7mm]

My first thought is variance in case neck thickness. Do you have a way to measure thickness at 4 points on case? You can also check run-out on bullet's bearing surface ahead of neck and compare to neck run-out.

 

[WildRose]

If it were me I'd try neck sizing only for a few rounds and see if that makes any difference.

The problem could very well be your chamber itself being slightly out of spec.

Did you have your Whiddon dies made off of the reamer your barrel was chambered with?

 

[cgordon]

Are the neck mouths square after fire forming? Did you trim and square them?

I didn't put them through the Wilson trimmer so I will do that. I also neck turned all the brass so neck wall thickness can't be out very much. I checked runout on the bullets in my Sinclair gauge and they are very good. And to wildrose I can't see the chamber being a issue as after fire forming and before resize the case is perfect under .001. I don't think it's the sizing die cause I sized all the new brass before they were shot and bullet run out was good.

 

[rcoody]

well looks like the only thing you changed was the neck collar. I would put the original one back in and give it a try.

could be when you changed them you put the new one in wrong or even whidden gets one wrong every now and then.

 

[gohring3006]

Double check and make sure the bullet tip isn't contacting the top of the seating stem.

 

[bigedp51]

Your Whidden seating die should be like the Redding and Forster benchrest seating dies and the case and bullet being held inline.

German Salizar did a seat die test of diffrent brands of seating dies and Redding type seating dies even had the ability to correct case neck runout. Meaning using this type die reduced/corrected bullet runout.

Below a excerpt from the seating die test by German Salizar.

"And now, the moment you've been waiting for... #1 - Redding Competition Seating Die (sliding sleeve type, threaded die) The Redding, which I expected to finish high, did what I thought couldn't be done - it produced rounds with an average runout that was less than the average case neck runout of the brass used. In none of the ten rounds loaded did the Redding increase the runout; it either held exactly the same or it decreased. The Redding, with an Average Runout Change of -0.0003" is the winner. The negative sign, of course, indicates a reduction in runout."

 

[FearNoWind]

Are the neck mouths square after fire forming? Did you trim and square them?

And - Do you clean the inside of the fired case necks?