runnout

[hardpan]

Guys,
I dont know if I am measuring right. I use a Neco Runnout gauge. Problem is that I don't get anywhere near the accuracy that THH mentioned, and I also use benchrest dies. Not sure if it is the measurement or actually is a real problem.. But, I would love to hear how you guys get to .000-.002 in runnout. I am closer to 0.005-0.010... Groups are good, 1/2" normally.

I neck turn and size in the same step. Then chamfer. I use forster benchrest dies. Partially seat the bullet, then bring it down, turn the cartridge a 1/4 turn, and then seat the rest of the way. Length is perfect, but I measure run out as in this pic

http://www.neconos.com/details.htm

thanks for educating me!
Hardpan

 

[Desert Fox]

I'm not familiar with Neco. I use Darryl Holland case run-out gauge and Sinclair's case neck micrometer caliper and neck turner.

Case quality, case preparation and the use of premium dies are the key to reduced bullet run-out. This is one aspect of reloading that can drive you nuts if not done correctly. The first thing you do is to segregate once fired cases according to their weight. Then measure case neck thickness on at least four places around the neck area and group them accordingly. You then do the customary case preparation work on the case like neck turning, squaring, chamfering etc,etc,etc. After you do all of these, you can then start reloading. I'll guarranty that you can keep that run-out to within .001 to .002 range and shrink your ES and SD to a single digit.

One caviat though! All these work are unnecessary for a hunting rifles that are factory made. If you have a custom that are capable of quarter minute accuracy, then go ahead and load your cartridge this way.

Here's one of those prep session for my 338 Lapua.

 

[rick smith]

Hardpan, There is a definite learning curve with any runout gauge. The amount of pressure placed on the bullet vs the amount/consistancy of pressure on the case as you roll it with your fingers is a fine balance. I use two different tools, Neco and Sinclair. I have the Neco setup for measuring bullets and the Sinclair for measuring cases. You first need to determine where run-out is being introduced into the case. Check the case neck of a fired, unsized case, size then check, seat bullet and check. Before you can correct run-out, you have to know where it is happening.

I have checked run-out using the seating method you described, doesn't make any difference. Good theory, poor application. I will guess that when you size and neck turn in one step you are using different tools?

Once you get to .005 or better you have a problem and you have to know where it is and what is causing it.Rick.

 

[woods]

Guys,
But, I would love to hear how you guys get to .000-.002 in runnout. Hardpan

Hey Hardpan

The most significant step I took in reducing runout was to start using the Lee Collet Neck Sizers. They are inexpensive and you might want to give one a try and see if they work for you. The principle is that there is a free floating specifically sized mandrel that goes into the neck and a set of collets squeezes the neck brass onto that free floating mandrel. Since the brass has been fire formed in your chamber and chambers are concentric, then the brass has no runout after firing. The Lee Collets preserve this through their free floating mandrel method. An added benefit is no lube in the neck.

A thread on adjustment is here

http://www.longrangehunting.com/forums/ ... ies-44360/

Most runout is created by the expander ball so if you can get rid of it then you are on your way. Another way to get rid of the expander is to use a bushing type die but outside neck turning is then mandatory to get good results.

Good brass is also important. If you have brass that varies more than .002" in thickness per side then even neck turning will not help. Reference this illustration

If the center of the neck is off-center then that will lead to runout no matter what you do.

There are a couple of methods to actually remove the runout as you measure it. One is the new Hornady tool which I don't know if it is available yet

and the other is the Bersin which I use and may be discontinued and was very expensive

The Bersin has taught me a few things through it's use:

New or freshly annealed brass is easy to push off center and create runout

The best way to get rid of runout is to not create it in the first place

Runout can be reduced to <.001" easily but very seldom completely eliminated, that sorta happens like one hole groups

Once you get your methods down to reduce runout to an acceptable level, then you can stop worrying about it because no further increase in accuracy will be discernible

Even if you push the bullet to reduce runout significantly, if the case neck is off center then all you have done is cant the bullet in the neck

Crimping with the Lee Factory Crimp Die also helps reduce runout


YMMV

 

[Antelope_Sniper]

Gentlemen, thanks for all the good information.
I think I need some lee Collet dies :twisted:

 

[woods]

I forgot, there is another way to size without an expander but that will depend upon your die.

Take the expander out of your Forster die, size a case and measure the outside diameter of the neck. If your die is not too constricted then it would be possible to turn the neck brass to a specific thickness to get the bullet grip you want and then size with that die sans expander.

Post your outside neck diameter after sizing without the expander and we will go through the math.

 

[.405]

I use the RCBS run out gauge.It is fairly easy to use.

http://www.midwayusa.com/viewproduct/?p ... ber=310955

I really like the looks of that Hornady tool.I may have to check that out when they are available.

 

[Antelope_Sniper]

Lee doesn't make a collet die for the 7mm STW. Guess I'll have to play with the 7 mag die and see if I can make it work.

 

[.405]

I use Redding Bushing Neck sizer dies and Competition Seater Die in my .308 target rifles. That eliminated any problems that I had with run out.

 

[boomer68]

Lee doesn't make a collet die for the 7mm STW. Guess I'll have to play with the 7 mag die and see if I can make it work.

I would be interested to know how you make out. I have a STW too and might end up ordering a custom collet set.

 

[kraky]

AAh yes....the great runnout demon. While I think it is good to make as straight of ammo as you can for consistant reloading be aware that runnout doesn't always make a good shooter bad.
Here is a post from LRH that I copied from a guy that has a gun that doesn't care in the least bit about runnout. While others post that any runnout over .005 will absolutely take a tack driver and turn it into a shotgun it isn't always true.
Just want to put this out there for those who are about to take the time and effort to try and tame this demon....do your own experiments and be sure any accuracy problems aren't caused by something else.


Here is the post as I copied it:

I would not worry about it, i'll bet you will still get good accuracy. When i necked down my 375 rum brass to 338 edge i was getting about 20 thousands runout with 338 rum neck sizing die. The accuracy with that much runout was great. My first group after load development was 3/4 inch at 325 yards. All 100 cases shot shot very good. After the first firing i get very little runout,but in all honesty they do not shoot any better than on mt first firing with a lot of runout. I think a good chamber will make up for a lot of runout. This probably won't be the normal for all rifles, but in my 338 edge runout does not seem to matter.

 

[woods]

Well you guys that want to use a Lee Collet on the 7 STW may have another option. The operable dimension is the distance from the case head to the junction of the neck/shoulder. On the 7 STW that is 2.572" and on the 7 mag is 2.229" so the difference is .343". If you could find a washer that would fit around the case head and was thicker than .343" then you could place it around the case head on top of the shell holder and fool the Collet die

or you could make one by drilling the appropriate size hole in a piece of aluminum of the right thickness.

I use the washer with the Lee Collet to leave part of the neck fire formed size

This washer is only about .1" thick.

 

[boomer68]

Great idea! I will have to give it a try. BTW, I use the Redding Boss also :wink:

 

[woods]

Another great way to reduce runout is to use a full length or neck sizing die without the expander ball. The inside of most dies are reamed very concentric like rifle chambers. The only problem is if the die has too small an inside diameter so that you can not turn the neck brass thin enough.

For example, If you take the expander ball out of your 7 STW die and size the neck and it measures .311" on the outside, then the math would be:

OD - caliber - bullet grip = total desired neck thickness
.311" - .284" - .003" = .024"

then:
total desired neck thickness / 2 = neck thickness each side
.024" / 2 = .012"

What this tells you is that you can outside neck turn to .012" and size without your expander ball and have .003" bullet grip.

You will have much more concentric brass without runout.

 

[boomer68]

woods : What is the best dies in your opinion?

 

[woods]

woods : What is the best dies in your opinion?

Hey boomer

If available, I prefer

Lee Collet Neck Sizer
Redding Body Die
RCBS Competition Seater
Lee Factory Crimp Die

If the Lee Collet Neck Sizer is not available then I will get a Redding Type S Bushng Neck Sizer since I can neck turn. If the RCBS Competition Seater is not available then I will get a Redding Competition Seater.

 

[boomer68]

Hi woods, thanks for the reply.

Do you neck turn all your cases, even hunting loads? I have never done this myself and wonder if it is needed.

 

[woods]

On 3 of my guns that have a tight chamber neck, it is necessary for me to outside neck turn in order to be able to chamber the brass. On all the factory guns I don't have to turn but do. You only have to do it once and it does not hurt. On one gun I have the Redding Bushing Die and since that die sizes the outside of the neck to a specific dimension and pushes all the variations to the inside of the neck where they bear on the bullet, neck turning is mandatory IMO.

In my mind it seems that brass has different expansion properties and gripping strength based upon it's thickness. Probably so very slight that it is indiscernible but like I said it doesn't hurt.

 

[30-338]

On one gun I have the Redding Bushing Die and since that die sizes the outside of the neck to a specific dimension and pushes all the variations to the inside of the neck where they bear on the bullet, neck turning is mandatory IMO.

I agree it's a good idea to turn necks using bushing dies or clean up the necks and the bushing does pushes the varations to the inside of the neck.

If your using bushing dies and don't what to turn necks Wislon will make custom inside neck reamers Sinclar keeps 22,6mm and 30cal in stock plus for the tight neck 22 and 6mm cal.

Most time a bullet will act as and expander and push the variation in neck thickness to the outside. Good way to check that is pull the bullet and the runout should be the same.

Here is good article on turning neck for a factory rifle
http://blog.sinclairintl.com/2009/02/19 ... ry-rifles/

 

[Ol` Joe]

Woods, I`ve found the collet dies always leave a small ring at the shoulder/neck junction due to Lee allowing clearance for the difference in headspace from various chambers. The die is built to allow for the max headspace and still work without the shoulder interfering. A tight headspaced chamber will show on the sized case easily.
I have been useing a sizer minus the expander ball for sometime now. I agree, it work great reducing runout as close to zero as one could wish. I use a universal decapper, and size after cleaning this way.
Some thicker brass I run the expander back in as a second step, just enough to open the mouths without resizing the case. This seems to work as well as without the expander, but is an added step.