Help with brass prep...Too much run-out.

W

Wheres_Waldo

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I cant seem to minimize the run-out on my 300 WM brass.

After careful processing, I'm still at .002" - .005" runout on the neck.

I was hoping to be around none to .002" but its just not happening!

Virgin R-P 300 WM brass.
Trued pockets and Flash holes.
Trimmed, Deburred and Chamfer
Mandreled and turned....My turner w/ indicator is reading none - .001" run-out on the neck in my K&M Turner
Neck sized w/ RCBS GM Bushing neck die, .326"

The same indicator is reading .002" - .005" on my Master guage...Kind of odd?

I seated a bullet and was getting .003" neck tension...a little tight but close enough.

RCBS GM Match bushing neck die was used to size the necks.
I was using this tutorial as a reference...http://www.6mmbr.com/jgcaseprep.html

Do yall think once fire formed and neck sized again, run out will deminish somewhat, as long as my chamber is concentric?
 
New cases still have some banana in them.
Fireform them and they should straighten up better .
 
J. Valentine got it right. You have to fireform them first. Some of the 22-100 ppc's I make would scare you to death before there shot. Also, you will probably get more runout neck sizing than Full-Length sizing.

It still baffles me how why neck sizing is still so popular....it has little to no use.

Hovis
 
As above, fireforming won't hurt, but I still had problems getting under .002 T.I.R. with a standard resizing die. I switched to a Lee collet die and now I have everything under .002 and most in the .001 T.I.R. It is the most accurate die I've ever used, but it doesn't set the shoulder back any. I still have to full length resize every 3 to 5 firings.
 
clowdis said:
As above, fireforming won't hurt, but I still had problems getting under .002 T.I.R. with a standard resizing die. I switched to a Lee collet die and now I have everything under .002 and most in the .001 T.I.R. It is the most accurate die I've ever used, but it doesn't set the shoulder back any. I still have to full length resize every 3 to 5 firings.
Click to expand...

The biggest problem is typical Full-length dies is how there set up. I don't feel like typing a big post again but search my posts and you will find the ones where I explain die set-ups.

Hovis
 
I buy Redding full length dies, send them to Redding with 2 fired cases and they hone the necks for $20 to what they need to be. I get less runnout this way than any other method I have used. Lose the expander ball.
 
Runout

IMHO you're not going to get it down to .002 by fireforming or sizing. You have to start with quality brass. The Lapua I've been using gives me <.0005 runout with a seated bullet. Remington 22.250 brass >.003.
I'm not sure that it really matters at that point, but it's nice to know you've eliminated a variable.
 
I chased this dog before

and I chased it more than once around the block.

The simple answer is:::::It's the BRASS!

I changed to Lapua and no longer have problems.

I get no more than .0015 runout on the bullet.

I will not build a rifle unless I can use Lapua brass.

You have a 300 WM tight-neck?

BTW Lee Collect Dies really work great.
 
Wheres_Waldo said:
I cant seem to minimize the run-out on my 300 WM brass.

After careful processing, I'm still at .002" - .005" runout on the neck.

I was hoping to be around none to .002" but its just not happening!

Virgin R-P 300 WM brass.
Trued pockets and Flash holes.
Trimmed, Deburred and Chamfer
Mandreled and turned....My turner w/ indicator is reading none - .001" run-out on the neck in my K&M Turner
Neck sized w/ RCBS GM Bushing neck die, .326"

The same indicator is reading .002" - .005" on my Master guage...Kind of odd?

I seated a bullet and was getting .003" neck tension...a little tight but close enough.

RCBS GM Match bushing neck die was used to size the necks.
I was using this tutorial as a reference...http://www.6mmbr.com/jgcaseprep.html

Do yall think once fire formed and neck sized again, run out will deminish somewhat, as long as my chamber is concentric?
Click to expand...
You don't actually say you have a tight neck chamber?
The tutorial is quite good. However if you are neck turning for a standard chamber then partial neck sizing should work best. This regains the lost brass diameter for the unsized section of the case neck. Works hand in hand with a body die that will never touch this expanded section of neck . Keep it short.
 
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Its not about head spacing its about getting the neck as centered as possible with a turned neck case in a standard chamber. The belt will not do that as well IMHO.
If he has a tight neck chamber then it does not really apply.
 
J. Valentine said:
Its not about head spacing its about getting the neck as centered as possible with a turned neck case in a standard chamber. The belt will not do that as well IMHO.
If he has a tight neck chamber then it does not really apply.
Click to expand...

How can a turned case neck in a standard chamber do anything but INCREASE in-bore yaw? Any "centering" offered by the loaded round is an illusion, the bullet WILL slap up against the side of the neck as the hammer drives it onto the bore.

"Concentricity of the loaded round" is completely meaningless with sloppy tolerances.

Incidentally unfired brass CANNOT be straight or "concentric", it's formed in a hammermill. Only your rifle's chamber can make it straight.

al
 
Al,
A friend who went from a tight neck .223 to a close neck found that the close neck was more sensitive to brass quality, and loaded round runout that is the result of poor quality.

For my tight necked 6PPC I have found that loading with the bullet into the rifling produces a straightening effect (closing the bolt) that does not take place when I jump the bullets, which places a greater premium on concentricity for the jumped rounds. Neither of these situations involves a factory barrel or chamber, but I thought that they might be of interest.
 
Quite some time ago, someone did some extensive testing to determine if bullet runout makes a difference on target. Bottom line was it seemed to make no difference. I have taken painstaking measures at times to prepare & shoot low runout rounds and my groups did not seem to benefit. With tight neck chambers and minimally sized cases I'm not sure it makes any difference. The runout can only be so much with the chambered round, even if you are jumping bullets which I often have done. I'd be interested to hear if anyone else has done extensive testing in this area.
 
alinwa said:
How can a turned case neck in a standard chamber do anything but INCREASE in-bore yaw? Any "centering" offered by the loaded round is an illusion, the bullet WILL slap up against the side of the neck as the hammer drives it onto the bore.

"Concentricity of the loaded round" is completely meaningless with sloppy tolerances.

Incidentally unfired brass CANNOT be straight or "concentric", it's formed in a hammermill. Only your rifle's chamber can make it straight.

al
Click to expand...

This is how you do it . The case neck is only partialy sized along its length. This leaves an expanded section of the neck that never gets sized EVER using a bushing neck die or a modified collet die.
The body and shoulder is sized with a BODY die ( when required )that does not touch ANY of the neck.
As a result the excess slap as you call it , is REGAINED for that portion of the neck that is NEVER sized again. Keep it short to allow easy chambering and enough sized neck for good grip on the bullet .
I started this idea with the 222 Rem. and its long neck was perfect for this in a bolt action. I still use it in cartridges like 223 Rem, 22-250 Rem , 308W, today but only for bolt action guns.
I know it works because I have been doing it for 30 years before Redding or anybody else even sold body dies . I invented my own body die system 30 years ago by cutting the tops off standard full length sizing dies and grinding out the neck area to create a crude body die . I'm sure others did the same things in other places in the world.
It will center a neck turned case in a factory chamber better than a belt will.
That is all I am saying. Is it going to suit the 300 WBY ? Well he will have to try it and see. Hell we dont even know if he is using a tight neck chamber or a factory chamber yet because the original poster has dropped out of his own thread. I have never used it on a belted case so I cant say for sure.
It works good on normal rimless bottle neck cases especially smaller calibers.
The only issue that might arrise is , if the unsized second shoulder starts to take over the head spacing job as the case getts tighter with multiple firings.
One of those things you just have to try and if you don't like it don't use it.
 
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Boyd Allen said:
Al,
A friend who went from a tight neck .223 to a close neck found that the close neck was more sensitive to brass quality, and loaded round runout that is the result of poor quality.

For my tight necked 6PPC I have found that loading with the bullet into the rifling produces a straightening effect (closing the bolt) that does not take place when I jump the bullets, which places a greater premium on concentricity for the jumped rounds. Neither of these situations involves a factory barrel or chamber, but I thought that they might be of interest.
Click to expand...

With a neat fitting straight fireformed case in a straight tight neck chamber
what is happening is the bullet is being started into the lands by a column of unburnt powder.
When it jumps to the lands it can be started off center , when it is allready in the lands it starts straighter.
The more accurate custom machined tight neck chambers and accurate turned brass with flat based bullets minimise this effect. So some guns shoot just as well jumping the bullets as seating into the lands and some others will show a slight difference.
 
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J. Valentine said:
This is how you do it . The case neck is only partialy sized along its length. This leaves an expanded section of the neck that never gets sized EVER using a bushing neck die or a modified collet die.
The body and shoulder is sized with a BODY die ( when required )that does not touch ANY of the neck.
As a result the excess slap as you call it , is REGAINED for that portion of the neck that is NEVER sized again. Keep it short to allow easy chambering and enough sized neck for good grip on the bullet .
I started this idea with the 222 Rem. and its long neck was perfect for this in a bolt action. I still use it in cartridges like 223 Rem, 22-250 Rem , 308W, today but only for bolt action guns.
I know it works because I have been doing it for 30 years before Redding or anybody else even sold body dies . I invented my own body die system 30 years ago by cutting the tops off standard full length sizing dies and grinding out the neck area to create a crude body die . I'm sure others did the same things in other places in the world.
It will center a neck turned case in a factory chamber better than a belt will.
That is all I am saying. Is it going to suit the 300 WBY ? Well he will have to try it and see. Hell we dont even know if he is using a tight neck chamber or a factory chamber yet because the original poster has dropped out of his own thread. I have never used it on a belted case so I cant say for sure.
It works good on normal rimless bottle neck cases especially smaller calibers.
The only issue that might arrise is , if the unsized second shoulder starts to take over the head spacing job as the case getts tighter with multiple firings.
One of those things you just have to try and if you don't like it don't use it.
Click to expand...

J.Valentine,

While I agree with your premise as far as centering the case (I've got maybe the only Neil Jones die with stepped neck/shoulder bushings) what I'm saying is that the neck will slap open to seal, it will completely let go of the bullet BEFORE the bullet enters the lands. The bullet WILL be slapped against the neckwall. The reason for fitted necks is to decrease this tolerance, so that the neck brass can act as a centering bushing, guiding the base of the bullet into the lands.

My point is that if you're shooting a "loose neck" chamber with say .008 of slop, the bullet WILL be cocked at least .004, or half of that. Turning the neck so that it's thinner will only increase this in-bore yaw.

al
 
True , the section of case neck that is smaller in diameter than the actual chamber neck dimention does expand more than if it is not turned in the first instance.
However if it is turned it expands evenly and concentricly and also releases the bullet with more precise neck tension because it is an even thickness .
If the case neck is centered by partial neck sizing leaving a permanent expanded section at the neck junction and also the bullet is already touching the lands then there is going to be a lot less inbore yaw than a case that is neck turned and "not " using partial neck sizing in a FACTORY CHAMBER .
Most factory chambers are so sloppy in the neck area that the standard case neck eventually expands to way bigger than the bullet anyway without doing any turning.
However they suffer uneven expansion and uneven neck tension while releasing the bullet.
It has been my experience that the junction of the neck and shoulder is a problem area when it comes to precision bullet release .
* Part * of why tight neck chambers work better is the fact that they REDUCE the effect that the neck junction has on the neck tension and bullet release concentricity due to the fact that the neck is not expanding very far to release the bullet and this nullifies the neck junction from the tendency to create a tapered less even release.
Partial neck sizing does a very similar thing by moving the bullet release away from the neck junction because it is already expanded to chamber diameter or close to it . This helps the turned neck in a * factory * chamber situation.
The bullet is initially moved into the lands by a coloumn of unburnt powder with only minimul amounts of gass at the perifery of that coloumn at that point in time. The bullet is already starting into the bore with or without any yaw by the time that actual full gass pressure expands the neck all the way to the chamber wall.
So the bullet has practicly left the neck before the actual full slap to the chamber wall happens.
I am not saying that yaw can't happen it can.
However I am saying that an even concentric release is better than just having less neck clearance and an uneven non concentric release from an unturned case neck that may be very uneven in wall thickness .
Good brass will always perform better than poor brass. Notwithstanding the partial neck sizing afore mentioned.


You are missing the whole point of the exercise .

To gain some of the benifits of neck turning in a " FACTORY CHAMBER ".
NOT! TO COMPARE IT WITH NECK TURNING IN A " TIGHT NECK CHAMBER "! WHICH IS WHAT YOU ARE DOING.
OFCOURSE IT IS NOT AS GOOD AS A FITTED NECK ! THAT IS NOT THE CONTENTION.

Believe what ever you like , I know it works because I have been doing it for a very long time.
It may not be suitable for everyone or every kind of gun but very little is.
PS . It also has one other advantage . It reduces the effects of neck welding in ammo that is pre loaded for a long time and has the bullet base below the neck junction , because its the neck junction area that exerts the most extra grip on the bullet from age hardening of the brass.
 
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I'm not missing any point at all.

I'm simply saying there's NO GAIN in turning for a sloppy factory neck. Not a comparison at all, simply no gain.

And statements like this "It may not be suitable for everyone or every kind of gun but very little is", do little to make your point. ALL accurate systems share many characteristics as do all inaccurate ones. It AIN'T all luck!

al
 
You are welcome to believe whatever you like.

alinwa said , " And statements like this " It may not be suitable for everyone or every kind of gun but very little is", do little to make your point. ALL accurate systems share many characteristics as do all inaccurate ones. It AIN'T all luck!

I'm talking about peoples abillities and types of actions etc. in a nice way .
Another good thread bites the dust.
 
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