Identifying the cause of my Bullet Runout

[tnemev]

Need some advice on where to go next. I'm thinking that the problem is my seating die.

Here's the situation. I'm getting runout of .007 to .012 on some reloads for my 30-06. I'm using standard RCBS dies. I don't have this issue when I reload for one of my other cartridges.

Here are the things I've checked. Runout is checked with the Sinclair gauge.

* Fire formed cases have .001 or less neck runout
* Neck runout averages .001 after resizing
* After bullet seating, the neck runout increases to .003 to .005 and the bullet runout is .007 to .012
* I changed out the seating stem from another RCBS die set of the same caliber, not any better
* Tried different bullet lots and brands
* Tried a different press

Nothing I have tried is correcting the issue.

I would appreciate some opinions from others before I throw money at a better seating die.

Thx

 

[Mutt]

Re: Identifying the cause of my Bullet Runout

Change your die.

Mic your necks.

 

[427Cobra]

Re: Identifying the cause of my Bullet Runout

Too much neck tension, lack of lube inside the neck during seating, burnt powder needs to be brushed out, what's left acts as a lube, brass cleaned with SS media or US needs a dry lube of some sort, seat your ammo in multiple steps, turning the case, seat a little, and so on, bullets need to start the seating process straight to end up straight, while RCBS does make decent equipment, a sliding sleeve seating die like a Redding Comp or Forster Micrometer are far superior to plano dies from other manufactures.

 

[1lnbrdg]

Re: Identifying the cause of my Bullet Runout

Forester Seating die.

Was seating with RCBS's competition die with .007+ runout, went to the Forester die, most under .002, none over .003.

The Redding seating die will do as well but with their softer stem, I recommend the Forester.

 

[tnemev]

Re: Identifying the cause of my Bullet Runout

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 427Cobra</div><div class="ubbcode-body">Too much neck tension, lack of lube inside the neck during seating, burnt powder needs to be brushed out, what's left acts as a lube, brass cleaned with SS media or US needs a dry lube of some sort, seat your ammo in multiple steps, turning the case, seat a little, and so on, bullets need to start the seating process straight to end up straight, while RCBS does make decent equipment, a sliding sleeve seating die like a Redding Comp or Forster Micrometer are far superior to plano dies from other manufactures. </div></div>

Neck tension is light. Case mouths brushed and lubed prior to sizing. Expander ball is polished to reduce drag. I even tried sizing without the expander ball. I also seat in multiple steps (partial seat, rotate case, seat). It looks like responses are pointing towards the seating die. I also tried different brands of brass to no avail.

 

[MitchAlsup]

Re: Identifying the cause of my Bullet Runout

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ng500</div><div class="ubbcode-body">
* Fire formed cases have .001 or less neck runout
* Neck runout averages .001 after resizing</div></div>

This indicates it is NOT your dies or your press.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
* After bullet seating, the neck runout increases to .003 to .005 and the bullet runout is .007 to .012</div></div>

A) check for uniformity of neck thickness--that is the neck could be concentric on the outside, and nonconcentric on the inside.
B) measure the outside neck diameter before seating a bullet, then again after seating a bullet--My guess is that you have too much neck tension
C) when seating bullets, cozy the case+bullet up into the die, and then feel the bullet slide into the neck with the hand you put on the lever. The bullet should slide in smoothly with an even amount of force.
D) also check that your chamfer is deep enough onto the case neck.

 

[MALLARD]

Re: Identifying the cause of my Bullet Runout

run your press slower both sizing and seating, get o-rings to fit between your lock collar and press

 

[leadbullet]

Re: Identifying the cause of my Bullet Runout

clean your seater die stem, when seating bullets, raise the ram all the way up then lower it, rotate case half turn and re raise the ram. Check run out.

 

[former naval person]

Re: Identifying the cause of my Bullet Runout

Add to MALLARD and attherange...put "O" rings between the die and press AND under the lock ring on the seating stem, allowing it to float. I do find better results with the Forster and Redding seating dies with the floating chamber. JMHO

 

[jcann]

Re: Identifying the cause of my Bullet Runout

+1 with what MitchAlsup said

 

[tnemev]

Re: Identifying the cause of my Bullet Runout

Thx for all the suggestions! I'll start with the O-rings and go from there.

 

[YAOG]

Re: Identifying the cause of my Bullet Runout

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ng500</div><div class="ubbcode-body">Thx for all the suggestions! I'll start with the O-rings and go from there. </div></div>

Floating your seater may help a little. But an O-ring cannot correct for case neck thickness variations causing the case neck's bullet axis being off center.

Do you have a ball mic and did you measure the problem cases to see how much the case necks vary around the neck? My 40 year old .308 R&P brass reloaded 20x plus times show case neck thickness variations up to 0.0003" but my neck TIR hovers at 0.001" average on my Sinclair concentricity gauge. Some cases will indicate a bit higher and some will indicate 0.000" but this is the average result. The funny thing is that they all shoot about the same.

I use Redding Competition and Type S F/L bushing dies with a Redding Competition bullet seater mounted in a modified Dillon 550B press with Whidden CnC floating toolheads pinned with UniqueTek clamping kit and Turbo Bearing.

 

[Deadshot2]

Re: Identifying the cause of my Bullet Runout


When you say "seating stem" are you referring to a threaded rod with a pusher plug attached to it? Or are you referring to a floating plug that is adjusted by a separate screw/threaded plug.

The only RCBS seater die I have is the former.

I get far lower run-out from my finished rounds when using a die with the floating plug, even my Lee seater die. The plug tends to center the bullet better before the pressure of insertion begins.

Whatever method your die uses, make sure that the "plug" is clean of all lube and chips that might cause the bullet to be started off center.

 

[tnemev]

Re: Identifying the cause of my Bullet Runout

Problem solved. It was the brass. I purchased a Redding Case Neck Concentricity Gage, sorted the brass. Runout is now measuring .001-.002. Thx for all the help!