Runout increasing when seating

[Alan Griffith]

I've taken the advice of members of this board, especially Kirby Allen's, and have gotten my runout down to .001" on the necks of my FL sized 30-06 brass. It's the runout after seating which has got me stumped. Some facts to follow:

-Winchester brand 30-06 brass, fired 4-5 times.
-Primers punched out via a seperate Lyman Universal decapping die.
-Sized with Forster BR dies so shoulder is not set back but just touched. Cleaned up the sizing die very well to make sure accumulated crud was not introducing variances. Sized the case without the expander button and checked runout which equalled only .0005". Did this to see if the expander button did/did not introduce runout. Once I sized the cases with the expander button set as Kirby Allen suggested, I was getting a max of .001" runout.
-Concentricity device is the Sinclair.

-I've really focused on cleaning up the necks with 000 steel wool inside and out.
-Neck thickness varies from .001" to .0035" thick. This may be the varible I'm lookig for!
-Device I use to measure thickness is the Sinclair MIC-4 thickness gage.
-Neck length is trimmed to 2.484" via the Forster trimmer and chamfered with the Lyman VLD tool.
-I'm using a Forster Ultra seater die. Nothing unusual about how I have this set.
-OAL is about 3.556", or about 1/2 the neck has bullet bearing surface in it.

Any suggestions on what I could do to get rid of the runout I'm getting at the seating station which runs upto .005"? I'm getting stuff which runs as low as .0015".

 

[Fiftydriver]

GSSP,

How are you setting up your seating die, from threading it into the press to seating bullets, let us know your set up steps. We can go from there.

Generally, if your getting neck run outs in the 1 thou range or less and using a seater like you are, your bullet run outs should be well under 2 thou consistantly and generally no more then 1 thou.

Let us know. you may have a bad seater or there maybe something in your seating die set up that is causing issues.

Good Shooting!!

Kirby Allen(50)

 

[abinok]

Totally agree with kirby, with the FB die, you should be seeing much less runout than you are. I suspect you are seeing case neck thickness variations manafest as runout. That one of the problems of outside sizing brass that hasn't been neck turned. The outside gets round, and the inside gets egg shaped to whatever degree your neck walls vary in thickness. After the bullet gets seated, these variations get pushed back to the outside of the case where your gauge sees them as runout. Ill bet youll nottice a correlation between measured TIR after seating, and neck thickness variations if you check some cases that have very consistantly thick necks to some that have .003" or more variation.

 

[distantfoe]

Too bad there wasn't a way to "iron" out the variances after resizing. I've done this a few times by running an expanding mandrel through the neck after resizing. The problem this creates is a lack of neck tension. Might just turn the necks, it's not too hard and you'll only have to do it one time. (unless a doughnut pops up - then that's easily cleaned up)

As for the runout inhereted when seating, I've gone to a hand die which has elimitated this problem. The hand die is worth the money for ease of set up and they stay set up even when switching to a different caliber unlike a standard press.

 

[abinok]

how do you mean that you can "iron out the variances" with a mandrel after resizing? perhaps you mean from a bushing die with no expander? if thats all you want to acomplish, just turn the mandrel down to the diameter approprate for the bullet youre using. Piece of cake. The neck thickness variation will still be there however. just on the outside instead of the inside.

 

[Alan Griffith]

Kirby,

For purposes of load development at the range, I use the little Lee Press with the Forster Ultra seater "locked" in so my OAL does not change. I believe I'm using a Lee shell holder. It's has a "1" on it and is knurled abound the circumfrence.

I simply followed Forsters instructions on setting up the die. I screwed the die down until it touched the shell holder. I kept screwing it down, compressing the spring loaded floating/sliding chamber upwards about 1/2 it's exposed length. I then tightened the lock ring down and locked it in via the lock screw. I then loosened the lock nut on top of the die and adjusted the bullet seating stem until a dummy round was near the depth I wanted it. From their I locked the lock nut down and did any final adjustments via the Micro Body.

As a test, I tore the seater die apart, cleaned it and reassemble it. I found a little reside of ? in side and it had a small ring of what looked like rust just inside the entrance. I reseated 3 rounds. Two improved by .002" from .005" to .003" and one stayed the same .0035". Was this a statistical improvement? I think not. As a side note, while the die was apart, I tried 180 BT's, 180 IB's, 200 Speer's and Hornady 125 Sp in the seater stem and did not notice anything askew such as large amounts of bullet wiggle.

I have a Forster trimmer I bought over 20 years ago and have the Outside Neck turner tool. I know I have stuff necessary for .224 diameter. I'll need to see if I have .308 cal stuff or if I'll need to order it; if we feel I need to turn necks!

As a control test, I have 100 virgin Lapua brass which I have only run through the FL size die and trued up the primer pockets. Haven't had a chance to check any concentricity or neck wall thickness yet.

Keep on Patterning

Big Al

 

[distantfoe]

[ QUOTE ]
how do you mean that you can "iron out the variances" with a mandrel after resizing? perhaps you mean from a bushing die with no expander? if thats all you want to acomplish, just turn the mandrel down to the diameter approprate for the bullet youre using. Piece of cake. The neck thickness variation will still be there however. just on the outside instead of the inside

[/ QUOTE ] Bullet run out will not be effected if the highs and lows are on the outside of the neck.

 

[abinok]

Exactly /ubbthreads/images/graemlins/smile.gif

 

[älg]

won´t this affect the way the case neck conforms to the rifle??

Abinok, I guess you could avoid the problem by using the mandrel and neck turning afterwards??

That´s kind of what i was thinking with the 300 rum cases I´m preparing.Don´t have a mandrel but running them through the expander should make the neck round, as you suggested, , then turn the necks to diminish neck wall thickness variations; and probably after resising necks with the proper bushing the mandrel should be used again??

it is however curious to see that cases run through the expander have a tight enough neck as to not allow a bullet to be seated by hand, and they have exactly the right size to be turned in a Forster neck turning device with the forster 30 cal. pilot.

 

[abinok]

[ QUOTE ]
won´t this affect the way the case neck conforms to the rifle??

[/ QUOTE ]
Nope. The neck will open the same no matter what. Too much variation in neck thickness will cause one side to release earlier than another... but folks could argue all day about how much differance it makes. With .001" variation or less... I don't worry at all, and on closer range ammo, .002" dosen't give nightmares.
[ QUOTE ]
Abinok, I guess you could avoid the problem by using the mandrel and neck turning afterwards??

[/ QUOTE ]
Right on with the mandrel. it pushes any thickness variations to the outside for the tool to wack off. I really like my Lee collet die for neck turning duties. I can turn a mandrel down to whatever size fits the cutter mandrel best, and im good to go! $5 fix... and cheaper than most any other option. Got a mandrel turned down to fit my neck thickness tool as well... for sorting brass to batch... or before neck turning.

[ QUOTE ]
and probably after resising necks with the proper bushing the mandrel should be used again??


[/ QUOTE ]

You could, but its not a requirement. I like to work the body and neck in seperate sizing operations... maybe im weird. with the approprate bushing, and neck turned cases, you could just do it with a bushing and no expander. Making the last sizing on the neck an inside sizing is realy only mandatory on unturned necks with more than... oh... .001" neck thickness variation or so.