Confused About How To Get Concentricity

[dariof]

The runout of my brass is anywhere between .001 and .006 after FL resizing. I'm using mostly Lake City, but do have mixed headstamps.

How do I make the brass more concentric??? I have read so much and am still unable to get a consistent .001-.002.

Do I:

Turn the necks for OD.....but then what about ID
Anneal
Use top quality sizing dies....I'm using a FL Redding 'S' die, but my Dillon gives me less runout.

Your input would be appreciated.....I am frustrated because I know I am doing something wrong, but can't pinpoint it.

 

[ZiaHunter]

The two main contributors to runout are non uniform case wall thickness in individual cases and the expander plug. You mention that you are using a Type S FL die which I assume has a bushing. Remove the expander plug and size some cases and check the runout. Hopefully this will reduce the runout but could potentially yield uneven neck tension due to non uniform neck wall thickness from case to case. To measure neck wall thickness you will need a ball micrometer. Neck turning will produce uniform neck wall thickness which will help reduce runout but is a time consuming process. Annealing will generally provide more uniform sizing as well as extend case life. I am surprised that your Dillon is producing less runout than the S Type dies because the opposite is generally the case. BTW I do turn the necks during initial case prep for my precision bolt guns.

 

[dariof]

The two main contributors to runout are non uniform case wall thickness in individual cases and the expander plug. You mention that you are using a Type S FL die which I assume has a bushing. Remove the expander plug and size some cases and check the runout. Hopefully this will reduce the runout but could potentially yield uneven neck tension due to non uniform neck wall thickness from case to case. To measure neck wall thickness you will need a ball micrometer. Neck turning will produce uniform neck wall thickness which will help reduce runout but is a time consuming process. Annealing will generally provide more uniform sizing as well as extend case life. I am surprised that your Dillon is producing less runout than the S Type dies because the opposite is generally the case. BTW I do turn the necks during initial case prep for my precision bolt guns.

Yes, I am using a bushing.....245 or .001 under the .246 OD of a loaded 223 round.

I have resized brass with the expander ball out of the Redding die, and the cases actually got worst. I know that sounds crazy, but my Sinclair concentricity gauge is very accurate.

Tomorrow I will call Redding. My buddy just got one of their dies and had to send it back becase it was denting brass, even when using the Redding lube.

I'm thinking if I start turning necks and annealing, the concentricity should improve.....hopefully. These are the two things
I am not doing.

 

[LRShooter101]

Per above,
- Consistency of the neck wall thickness can be a big culprit.
- Dies, while you are looking at your sizing die, don't forget about your seating die.

Bought one of these a while back:
Hornady Manufacturing Company :: Reloading :: Metallic Reloading :: Tools & Gauges :: Lock-N-Load® Ammunition Concentricity Tool :: Ammunition Concentricity Tool



By checking, and then using the "adjustment feature", I am able to catch and fix any problems quickly & easily.

This issue can be a "trip down the rabbit hole" if you are not careful! It will start with buying a new die, then you are neck turning, then you are seating bullets with a dedicated arbor press. Many hours and dollars later, you get it figured out and are happy with the results.

I am all for loading concentric ammo, but unless you are a Benchrest Shooter, you may or may not really see some of the results. Per above, I will double check it with the Hornady, and if it is significantly out I will fix it. With most of my brass, bullets, and dies, I am doing well enough that I don't really have any major issues.

Ultimately comes down to:
- How critical is your ammo/runout in the big picture
- How much are you willing to invest to eliminate runout

Hopefully you will get it all figured out.

 

[Chanonry]

Been there. I ended up speaking with the guys at Redding.

What you need to do is measure the concentricity of each case as you go and look for trends. Do mixed head stamps imply different number of loadings? You may have some necks that are hard and others still malleable. What is the concentricity before and after sizing on a case by case basis? What are the variations in neck thickness? You need to do the legwork I am afraid, otherwise suggestions are just guesses.

Separate the brass by head stamp and see how each behave.

Get some better data, look for trends then .

 

[seanhagerty]

Lets back up a minute. Is your ammo not accurate enough for the purpose you are currently or intending to use it for? If it is, do not chase this.

I load ammo on a dillon 550, with an RCBS X die, and make ammo plenty accurate for the tactical and f class matches I shoot in.

 

[dariof]

Lets back up a minute. Is your ammo not accurate enough for the purpose you are currently or intending to use it for? If it is, do not chase this.

I load ammo on a dillon 550, with an RCBS X die, and make ammo plenty accurate for the tactical and f class matches I shoot in.

I do get fliers here and there. Groups are decent, but then a round doesn't come close to the others. This is only at 10o yards......at 500, the error would be much greater.

 

[LRShooter101]

Go to this post, and scroll down to #61:
http://www.snipershide.com/shooting/sniper-hide-gunsmithing/214393-short-action-284-win-tactical-l-build-shilen-action-barrel-2.html#post3038151

You will see my comments on donuts/neck tension. Not that you are having issues with donuts, but consistent neck tension could also be an issue with some of your flyers. Using pin gages, I can quickly check a batch of re-sized brass to find out if any are over/under sized. This difference in internal neck diameter/neck tension is typically the result of using a bushing die on brass that has varying neck thickness.

It amazes me the number of people that size only with a neck bushing, and no type of internal expander, and expect consistent neck tension? Contrary to popular belief, both internal and external neck measurements can be critical, and only working one of them, will not necessarily guarantee the other.

You really need to check the consistency of the neck thickness in your brass, and that is all around the neck of a single case, as well as from piece to piece. If you have any level of variation, then it can lead to issues with runout and neck tension, both of which could impact accuracy. How much, obviously depends on how bad the variation is.

Only real way to deal with varying neck thickness, is to measure and sort, or neck turn it all to consistent thickness. There are obvious pros & cons to both options.

In most cases, I see people going to this level of preparation/work when they are chasing results in the 0.25-0.50 MOA range. I don't usually see this as being primary issue when you are talking about results that are 1.0 MOA plus. If the issue is that big, it is usually something else.

Not sure if I am reading your original post correctly? But if you are mixing various makes/types of brass into a single loading, there is not much of any chance that you are going to get consistent anything! Just using two different types of brass can result in completely different internal capacities, which translates into different pressures/velocities, which will obviously have a major impact on the results.

If you check the link below, it will show the various case capacities for a number of .308 cases (not sure what cal this is?):
The Rifleman's Journal: Cartridges: 1000 Yard .308 Case Capacity and Other Problems
Per that info, case capacity could range from as low as 53.45 to as high as 57.40.

Hard to track everything that could be going on here without more info, runout may only be one of the issues?

 

[dariof]

Go to this post, and scroll down to #61:
http://www.snipershide.com/shooting/sniper-hide-gunsmithing/214393-short-action-284-win-tactical-l-build-shilen-action-barrel-2.html#post3038151

You will see my comments on donuts/neck tension. Not that you are having issues with donuts, but consistent neck tension could also be an issue with some of your flyers. Using pin gages, I can quickly check a batch of re-sized brass to find out if any are over/under sized. This difference in internal neck diameter/neck tension is typically the result of using a bushing die on brass that has varying neck thickness.

It amazes me the number of people that size only with a neck bushing, and no type of internal expander, and expect consistent neck tension? Contrary to popular belief, both internal and external neck measurements can be critical, and only working one of them, will not necessarily guarantee the other.

You really need to check the consistency of the neck thickness in your brass, and that is all around the neck of a single case, as well as from piece to piece. If you have any level of variation, then it can lead to issues with runout and neck tension, both of which could impact accuracy. How much, obviously depends on how bad the variation is.

Only real way to deal with varying neck thickness, is to measure and sort, or neck turn it all to consistent thickness. There are obvious pros & cons to both options.

In most cases, I see people going to this level of preparation/work when they are chasing results in the 0.25-0.50 MOA range. I don't usually see this as being primary issue when you are talking about results that are 1.0 MOA plus. If the issue is that big, it is usually something else.

Not sure if I am reading your original post correctly? But if you are mixing various makes/types of brass into a single loading, there is not much of any chance that you are going to get consistent anything! Just using two different types of brass can result in completely different internal capacities, which translates into different pressures/velocities, which will obviously have a major impact on the results.

If you check the link below, it will show the various case capacities for a number of .308 cases (not sure what cal this is?):
The Rifleman's Journal: Cartridges: 1000 Yard .308 Case Capacity and Other Problems
Per that info, case capacity could range from as low as 53.45 to as high as 57.40.

Hard to track everything that could be going on here without more info, runout may only be one of the issues?

Thank you very much for your detailed answer. I am using different head stamps, and I realize now that would cause some consistency problems.

I just purchased Lapua brass, and plan on switching over to that. I also purchased a headspace gauge and a Redding carbide expander for my Redding S FL die. I'm thinking using the same headstamp with the S FL die (set corrdctly with the headspace gauge), I csn get ome bettrr concentricity.

I am not turning necks yet, but that's not out of the picture.

 

[seanhagerty]

Also, you didn't mention whether or not you did any load development. It may a good idea to visit Dan Newberry's OCW site if you haven't already gone through a load development process.

 

[LRShooter101]

If you are going with all Lapua brass, problem solved!

You can check and sort it, but most people are just good to load it with quality equipment and shoot it.

If you are going to run a neck bushing and expander, just make sure that you are not "overworking" your brass. You don't want to expand it on the way in, neck it down at the top, and then expand it again on the way out. You should not be moving your neck dimensions back and forth by more than .001-.002.

If you are running Lapua brass in a good bolt gun, you are actually good just neck sizing the brass for 2-3 firings. Then you can anneal / full length size / trim, then neck size for another 2-3 firings.

If your brass is going to be going into different rifles, it is getting beat up, or you have a "sloppy chamber", then the full length sizing every time makes sense.

Some people are sticklers for full length sizing every time, but it can come with a price in that it can "over work" the brass unnecessarily based on your chamber and die measurements.

Your headspace gauge will tell you how much your shoulder is moving out with each firing. If you don't notice that it is really moving, then there will not be a huge benefit to bumping it back between every firing.

When you become "intimately familiar" with your brass, and how it behaves with each firing, then you can come up with a reloading scheme that works best.

The key with the brass is having the right equipment to measure/check it with. Sounds like you have most of it, so now it just comes down to putting it to good use.

 

[Lumpy Grits]

dbl post
LG

 

[Lumpy Grits]

After you seat the bullet-Lower the press's ram and turn the rnd 180* and run the rnd all the way back into the seat'n die.
You'll also get lower run-out from FL size'n than just neck-most of the time.
X2 on annealing--
LG

 

[dariof]

Also, you didn't mention whether or not you did any load development. It may a good idea to visit Dan Newberry's OCW site if you haven't already gone through a load development process.

Yes, I do. First powder, then lands. Hopefully that is the correct order!

 

[seanhagerty]

Spend some time reading this site OCW Overview - Dan Newberry's OCW Load Development System

I am a huge fan of this method of load development. I bet your flyers go away once you develop a load with this method.

Sean

 

[rockier]

This may be a dump question but I will ask it.

How far out of concentric before it makes a differences to the groups?

 

[Lumpy Grits]

Well FGMM that I've ck'd is .003 TIR or less.
That's what "I" go by--
YMMV,
LG

 

[ULTRAEDGE]

Check your fired brass before resizing. You could have a chamber issue.

 

[Victor N TN]

Most benchrest shooters try to keep the runout to less than 0.002" After each firing I used a bronze / brass wire brush to clean the INSIDE of the case necks. As the brush wears a bit and gets looser, work some 000 steel wool into it and keep using the same brush until it quits cleaning for you.

If it's going to be a while before you shoot the brass, try rubbing some powder solvent on it then later flush with either alcohol or carb cleaner and let dry.

Good luck.
Victor

 

[jbell]

If you are going with all Lapua brass, problem solved!

This...

To add to it a little if you are measuring the concentricity of a loaded round measure it on the bearing surface of the bullet (just rear of the ogive) not out at the tip. Naturally most bullets will or can have some run out in front of the ogive but the bearing surface will be concentric.

If you are only measuring the brass and looking to solve a run out problem don't forget to measure before and after firing and noting the measurements (as stated). Also on the brass with a run out problem measured at the neck measure the wall thickness with a ball mic that has a vernier scale (also as stated above). But to add to it measure the body of the brass too. Do this in a few places, just behind the shoulder, mid way, and just in front of the head. This will tell you if you have a chamber problem (if you are only nk sizing). One other trick is to verify your die or even the press isn't the culprit. You can use a small o-ring under the lock ring to let the die self align. Also take the spring out of the shell holder slot on the ram, this will allow the shell holder to float keeping the shell holder from being off center of the die.

The switch to Lapua brass will more than likely solve your problem but I just thought I would throw these ideas out there. Good luck...