Excessive bullet run out. How to remedy?

[FUBAR]

As stated, in many, many words, "concentricity gauge" used in hand loading is a misnomer for the most part.

Just look up a machine concentricity gauge, the cost for a basic one is very high and they go up from their. They check x,y and z based on an objects center line...And if we did this level of quality control in hand loading, we would also have to make sure the case head is perfectly squared!

What most of us do, in simple terms, is check the "roundness" of the neck.

On my work I know where my runout is introduced, for me the biggest problem is with a couple of dies....

If one is really checking to an extreme level, like .000020, then they need extreme equipment, and I would think the round needs to be locked in the bolt at the very least, and really it needs to be in full battery!

But of course the above is just my take on the subject....

 

[Bart B]

I don't get it. Why would you want to "fix" a round that shows excessive runout as opposed to using the runout tool to correct the flaw in the process that is causing the runout in the first place?

If you're on a military team using issued ammo made at an arsenal or commercial factory, it helps to straighten the crooked ones.

I've done that and got twice the accuracy the crooked ammo produced. Unstraightened 7.62 NATO and .308 Win. ammo with runout up to 8/1000ths was straightened to have less than 3/1000ths. In mil spec and SAAMI spec chambers a bit on the large size, new cases shoot more accurate if their bullets are pretty darned straight with the case axis. 1 MOA accuracy at 600 yards is a lot better than 2 MOA.

 

[Mikecr]

No, we're not checking 'roundness'.
Our cartridges are not solid stock being turned to something centered on a lathe. They are tubes FORMED to something free from any center-line in our chamber & dies.

The best we can do is make STRAIGHT loaded ammo.
Straight ammo is also concentric ammo.
But concentric ammo is NOT straight, until measured so.
We can not subtract opposing readings with out of round assumptions, or bend one end of ammo and assume it's straight from one end to the other. It don't work that way.
Straight is just that, no bends/added stresses, and it passes all tests.

You 'fix' your forming process, and verify that formed is straight with measure.
It doesn't take smoke & mirrors, it takes methodic investigation and adjustment of your processes. I do this until my ammo is straight with every cartridge, and I've never regretted it.

A factory stamps out widgets, like we are doing here, and QC finds they aren't conforming to spec.
American QC(not red communist Chinese QC) does NOT go to bending widgets so that the out of conformance measure is 'technically' SAT -with required number of samples.
They stop the line, get together with maint/engineering, investigate/determine the cause, take appropriate actions to remove the cause, and verify they've mitigated further problems.
Just sayin, there is a right and wrong way to approach this.

As far as indicator accuracy here, anything under .0001 is usually masked by surface profile. I've tried it, it didn't work well for brass cases/bullet jackets.
I keep going back to .0005, as it provides resolution I can believe and mind for quick checks.
My only concern is >1thou of TIR, as I don't keep ammo beyond this.
If I had several in a batch that went there, I'd stop and find out what the schmuck(WTS).

 

[Goofycat]

Enjoy!

http://bulletin.accurateshooter.com/2012/04/tools-and-techniques-for-measuring-cartridge-brass/
The Rifleman's Journal: Reloading: Concentricity Tools
Who uses a concentricity gauge? - Sniper's Hide Forums
Hornady Concentricity Tool
NECO Product Descriptions
Hornady Manufacturing Company :: Reloading :: Metallic Reloading :: Tools & Gauges :: Lock-N-Load® Ammunition Concentricity Gauge :: Ammunition Concentricity Tool
Gear Review: Bruno Concentricity-Checking Tool « Daily Bulletin
Videos Show Functions of Hornady Concentricity Gauge « Daily Bulletin
Concentricity Gauge
Case Measuring Tools
Sinclair Inc Search : Reloading Equipment : Measuring Tools : Concentricity Gauges -
H&H Concentricity Gauge and Bullet Straightener « Daily Bulletin
Eccentricity « Daily Bulletin
21st Century's Impressive New Concentricity Gauge « Daily Bulletin
NEW Redding Case Neck Gauge « Daily Bulletin
http://www.longrangehunting.com/for...n-out-how-remedy-82028/index4.html#post671914
http://www.longrangehunting.com/forums/f28/wtb-concentricity-guage-42499/
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07-10-2012, 12:25 AM
boomtube on LRH
Platinum Member

Join Date: Oct 2007
Location: Mountians of SW NC, near Asheville
Posts: 1,296
Re: Concentricity gauge
"...I've noticed so far with my gauge. Lee and Hornady makes just as good ammo as the more expensive Redding dies..."

It's astonishing how a good set of tools can get us passed all the BS about who makes the 'best' dies and presses, and case brands and .... whatever. On average, I find no consistant difference between any brand of conventional dies, or presses no matter how purty or costly some are!

For me, the best average necks have come from Lee's Collet Neck sizer dies, used along with a body die for 'FL' sizing. And the only seaters I think qualify for the label of 'competition' dies are those by Forster and Redding. And that wasn't my opinion before I got a concentricity gage!

The 'best' way to measure runout is to position the gage at the point that shows the worst runout, don't try to find some mid point that reduces the gaged differences; that's only kidding ourselves. No matter how or where we measure it, the goal is to get runout to 'zero', not some present number. But we won't get there - consistantly - without tossing a lot of cases! Thus, each of us sets our own runout tolerance. Some of us do it by testing the results at the range; our targets tell us what our loads will do just as a concentricity gage tells us our runout. Seperate your loads into groups by levels of runout and see where your groups enlarge and by how much.

One thing to remember is actual runout is half of what the gage says.; TIR (total indicated runout) is the same error measured from two directions. Another thing is the max runout is limited by the chamber. Any chamber will force a badly bent round straighter, the amount of correction depends on how tight the leade fit is.

IMHO, the worst possible use of a concentricity gage is for bending the ammo straight. It can be done but the pressure can also damage thin jacketed bullets in the effort. The best use of a gage is to find where (and why) your runout is coming from so you can correct the cause. First check your sized cases; NO seater can make straight ammo in bent-neck cases.

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12-16-2010, 09:00 PM
B-P-UU on LRH
Junior Member

Join Date: Dec 2010
Posts: 9
Re: Hornady or Sinclair concentricity guage
This thread brought me out of the woodworks. Hello, I've been absorbing a lot of info from this site for a long time; truly great stuff. I would like to start off by saying I personally own none of the tools mentioned on this thread, so take this for what it's worth. I reload, just not to the level of some of the members of this site. I do, however, have experience applying runout to engineering prints.
MikeCR is 100% correct in stating "if you eliminate runout, your ammo will be concentric." The converse is not true, however; you can be 100% concentric and have lots of runout, as he also mentioned.
By definition (ASME Y14.5 GD&T Standard), the proper way to measure runout is by chucking the sample (in this case, a loaded round) via the datum you are comparing your dial indicator to (in the case of a loaded round, the case head) to find the center axis of the case (sorry, tried attaching pic to clear this up). Thus, the Sinclair tool mentioned does not actually measure runout; it references datum points on the case surface via rollers as opposed to referencing the case axis, the theoretical center of the case. To visualize this, imagine if the piece of brass was egg shaped. When rolling the loaded round, your dial indicator on the bullet would give readings all over the place. In that example, it is also possible the bullet is 100% concentric with the 'egg' shaped brass, even though your dial indicator says otherwise. While that may not be a likely scenario, dents or imperfections on the case body is. These imperfections would also show up on your indicator as 'false runout'.
From what I can tell, the Sinclair tool and tools like it are actually measuring bullet position with respect to the OD surface of the case as the reference datum. This isn't necessarily a bad thing, it just is not runout.
Unlike concentricity, runout also controls feature shape (roundness). In reloading, regardless of the measurement device used, you are making one fairly safe assumption: the bullet is perfectly round. God himself can prep your brass, but if your bullets are out of round, i.e., surface imperfections or a lobed surface (triangular w/ rounded corners), your dial indicator will bounce around.
Concentricity is much more difficult to control and measure. If dial indicators are used to measure concentricity, you really need two of them to do so. The dial indicators need to be 180 degrees apart and the case needs to be rotated, collecting data points each time you stop (this can be every 45 degrees, 15 degrees, etc.). Once data points are collected, the median points of the tolerance feature (bullet) must be within the tolerance zone of the case datum axis. Fuzzy? On a loaded round, you would need to collect data on the case as described above, calculate the center based on that data (MATH), then do the same for the bullet and compare the two values. CMM's are often used for this, collecting 100's to 1000's of points. The points are generated and math functions in the CMM are used to give you a magic 'center' number. These two 'center' numbers are then compared to the specified tolerance. Most reloading benches I've seen do not have CMM's.
For what it's worth, every time I've seen concentricity specified on a print, the author really means runout. Most shops don't understand concentricity well enough to accurately/reliably measure it – they can measure runout fairly easily though. Even the ASME Y14.5 Standard recommends using runout or true position instead of concentricity. The reason; it is often misused.
Finally, I cringe every time I hear someone say 'total runout' when measuring bullets with respect to the case. Total runout is measured similarly to runout with one exception; the dial indicator must be moved horizontally along the measured surface. Total runout applies to the ENTIRE surface. Although they seem similar, total runout controls concentricity, straightness, roundness, and taper. This is a big deal. Unless your bullets are perfectly straight with respect to case datum axis (achievable), round (achievable), concentric (tricky, but doable), and have zero taper (a bullet without an ogive), you are correct. If your bullets curve to a point like mine, you are measuring runout.
Looking purely at the design of Sinclair vs. Hornady, I would buy the Hornady to measure/correct bullet runout (with that being said, I have no idea what the gauge R&R is of either companies dial indicators – maybe they're both junk??). But if the runout is actually in the case mouth, the Hornady tool cannot correct that; that would need to be corrected by your die setup.
I hope I have not further confused those already confused or angered those who are shooting ridiculously small groups with their current setups. Good Luck.

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Mikecr on LRH, December, 200

Re: Concentricity gauge

I should have said it's 'tricky' as there is no malice in it.
And this is where it get's tricky;

Concentricity is taken only to CENTER axis.
If I alter something .001" from concentric, it would measure .002" TIR at the same point.
However, CENTERED ammo as measured isn't always so chambered, because it isn't always straight.

Cartridge total indicated runout[TIR] combines factors; banana shaped cases, offset necks, thickness variance, seating misalignment, and relative measurement errors. When we subtract our minimum reading from the maximum and take the absolute value, the result is our Total Indicated Runout.

The best we can get is STRAIGHT ammo, and TIR quantifies this better than concentricity (given available methods of measurement).
Load a round with zero TIR(straight) and it is concentric.
Load a concentric round, and TIR could still be ugly(not straight).

The best tool I'm aware of to measure TIR(and I've tested a few including H&H), is Sinclair's: Concentricity Gauges - Sinclair Conc. Gauge w/ Digital Indicator
They refer to it as a concentricity gauge, but it's actually a runout fixture, and does not measure concentricity at all. That's ok though, it works. And I can tell you that your ammo(concentric or not) is NOT straight until measured so on this Sinclair(or variant of).
So what is the difference?

Picture your bent ammo as a jump rope, with both ends pinned as typical.
To best define it's maximum displacement from straight, you'd place an indicator in the center of it's arc and measure TIR. Right?
You wouldn't put the indicator nearest one pinned end, as it would show lower runout than maximum(actual). Unless, you don't care about runout, and just want any indication off concentric. Let's say concentricity that you can adjust with pressure on bullet's seated....
So what about runout? What about getting the ammo straight?

Now back to the jump rope. Only this time you pin the center of arc, and one end slid to the same plane, and indicate displacement nearest the free end.
Now your showing every bit of the devil in it, and this is what the Sinclair does.
Your ammo is NOT straight until it measures low enough in runout, with this method.
Is it then concentric as well?
Yes, of course.

Consider a bit of what bent ammo does when chambered(concentric or not)..
Will it be aligned with the center axis of your bore? NO, IT NEVER WILL BE.
How do you get your ammo to consistently point(wherever it does)?
You make it the same,, STRAIGHT
Last edited by Mikecr; 12-16-2009 at 07:16 PM..

 

[Trickymissfit]

.000020 accuracy is commendable, but for purposes of bullet runout and realignment it would be a bit much; I mean, who can tweak bullets to such a minute amount? Accuracy out to ten thousandths seems to be the top end on practicality when working with cases and loaded cartridges; for my varmint-shooting accuracy at ranges of 400 yards maximum, I would opt for tolerance measurements in the .001" or .0001" ranges, unless someone else tells me differently.

I appreciate your reminder that we should always consider each point on an instrument that might offer the possibility of wear. If the instrument is to be used extensively for measuring thousands of rounds, for instance, I think that wear would be a serious consideration. For my purposes, I would be using a concentricity gauge only for quality-control purposes by taking sample concentricity/runout measurements only occasionally, thus making the wear factor not that important in the grand scheme of things. I.e., I see no reason to drive a Ferrari to go to the grocery store.


With the wear factor not holding much weight for my purposes, my concern would be more with the inherent lack of good design, materials and construction. Bad bearing material, for instance, would doom a gauge at the outset, as would bad design in their placement and rotation in the gauge itself. I haven't seen anything offered by any of the gauge manufacturers as to the accuracy of their instruments out-of-the-box and as to how long such accuracy would last. I assume we just trust them by buying their products and keep our fingers crossed? Such a shame that we don't have an outfit such as Consumers Reports so as to compare these items.....or do we?

that Rhan indicator was used with a special bracket to measure actual flatness of surface plates (smaller ones). It was pretty much worthless for anything else. The Federal electronic indicator would go down to one tenth of an arc second in a controlled atmosphere. Was deadly accurate, and a pain to use. I rarely used it (maybe two or three times), but did use the electronic level attachment all the time to align super precision machine centers. Much easier than doing it with a laser and more accurate. I just mentioned them to give us an idea whatkind of indicators are out there right now, and probably should have gone on into their uses. I have used .000050" indicators every now and then when trying to tweek a tenth or two out of something. They also are not something we would ever need here. I used to lap and scrape surface plates for a living (also large parallels and angle plates, etc). Doing this you gain a huge collection of measuring equipment, and learn to use it. Building machinery you learn to use lasers and the electronic levels, and soon learn you can't get by without them.

With my hand loads, I'd just love to do five tenths TIR all the time, but my equipment won't do it. I learned along time ago it was easier to tweek a tenth or two here and there to make big gains than it was to try and make a huge move todo the samething. Most of my loads fall into the .0015" range (TIR). That's why I like the five tenth indicators so much. But could make do with a good one thousandths indicator if I had to. (remember you can always split the graduations on the dial). And I honestly doubt that loading dies are any closer than .0005" for anything comming off the shelf. (they'll change that much from heat treat or even more.).
gary

 

[Trickymissfit]

"Rhan also sells a .000020" dial indicator,..."

A dial indicator that can resolve 20 millionths of an inch is pretty impressive but I doubt any reloader needs that. I have a few one thou and one tenth reading dial indicators and find that one thou is as good as I need to check bullet runout for my factory rifles, can't imagine the difficulty of working with something 50 times that sensitive!

it's a special use indicator. Never seen anything close to that ever used for anything but measuring surface plates. They did sell a version with a built in encoder, and my boss ran out and bought me two of them. Deadly accurate, but unusable! You could set there and watch the readout drift back and forth for five minutes! The Federal was just as accurate, but also prone to vibrations and drafts. Neither of these have a use in reloading.
gary

 

[Trickymissfit]

looking at the 21st Century gauge, I noticed that it uses rollers instead of ball bearings. If setup right they should be very accurate. I also liked the way the setup the dial indicator, although it looks like it would have been easier with a standard dove tail clamp made for the indicator. Anyway it looks like a nice outfit designed with some thought in mind.
gary

 

[Goofycat]

This article from the Blog section of 6mmBR, November 2005 is not directly related to concentricity gauges, but I thought it was worth a read:


"RELOADING TIP--Neck Tension vs. Time: We've learned that time (between neck-sizing operation and bullet seating) can have dramatic effects on neck tension. Controlling neck tension on your cases is a very, very important element of precision reloading. When neck tension is very uniform across all your brass, you'll see dramatic improvements in ES and SD, and your groups will shrink. Typically you'll also see fewer fliers.

Right now, most reloaders attempt to control neck tension by using different sized neck bushings. This does, indeed, affect how hard the neck grips your bullets. However, James Phillips recently discovered that another critical factor is at work. He loaded two sets of 22 Dasher brass. Each had been sized with the SAME bushing, however the first group was sized two weeks before loading, whereas the second group was neck-sized just the day before. James noticed immediately that the bullet seating effort was not the same for both sets of cases--not even close.

Using a K&M Arbor press equipped with the optional Bullet-Seating Force Gauge, James determined that over twice as much force was required to seat the bullets which had been neck-sized two weeks before. The dial read-out of seating force for the "older" cases was in the 60s, while the seating force for the recently-neck-sized cases was in the 20s. (These numbers correspond to pounds of force applied to the bullet). Conclusion? In the two weeks that had elapsed since neck-sizing, the necks continued to spring back (get tighter) and stiffen. Lesson learned: for match rounds, size ALL your cases at the same time. If you want to reduce neck tension, load immediately after sizing."

 

[Bart B]

IMHO, the worst possible use of a concentricity gage is for bending the ammo straight. It can be done but the pressure can also damage thin jacketed bullets in the effort. The best use of a gage is to find where (and why) your runout is coming from so you can correct the cause. First check your sized cases; NO seater can make straight ammo in bent-neck cases.

Good information.

All the crooked ammo I straightened up was done with a bullet puller. A .338" bullet collet was used to hold handloaded .30-.338 Win. Mag., 7.62 NATO and commercial .308 Win. ammo by the neck. Their neck diameters were somewhere between .336" and .338" so the case neck holding the bullet was well supported all the way around. Accuracy went from 2 MOA to 1 MOA at 600 yards with the NATO and commercial .308 stuff. Straightened .30-.338 Win. Mag. ammo with new cases went from just under 2 MOA at 1000 to 3/4 MOA after bending the case necks straight in the same collet. If the bullets were damaged in any way, I don't think it was enough to make a difference. Straight ammo (.003" bullet runout or less) shot as accurate as the ammo with straightened bullets.

 

[rscott5028]

This article from the Blog section of 6mmBR, November 2005 is not directly related to concentricity gauges, but I thought it was worth a read:


"RELOADING TIP--Neck Tension vs. Time: We've learned that time (between neck-sizing operation and bullet seating) can have dramatic effects on neck tension. Controlling neck tension on your cases is a very, very important element of precision reloading. When neck tension is very uniform across all your brass, you'll see dramatic improvements in ES and SD, and your groups will shrink. Typically you'll also see fewer fliers.

Right now, most reloaders attempt to control neck tension by using different sized neck bushings. This does, indeed, affect how hard the neck grips your bullets. However, James Phillips recently discovered that another critical factor is at work. He loaded two sets of 22 Dasher brass. Each had been sized with the SAME bushing, however the first group was sized two weeks before loading, whereas the second group was neck-sized just the day before. James noticed immediately that the bullet seating effort was not the same for both sets of cases--not even close.

Using a K&M Arbor press equipped with the optional Bullet-Seating Force Gauge, James determined that over twice as much force was required to seat the bullets which had been neck-sized two weeks before. The dial read-out of seating force for the "older" cases was in the 60s, while the seating force for the recently-neck-sized cases was in the 20s. (These numbers correspond to pounds of force applied to the bullet). Conclusion? In the two weeks that had elapsed since neck-sizing, the necks continued to spring back (get tighter) and stiffen. Lesson learned: for match rounds, size ALL your cases at the same time. If you want to reduce neck tension, load immediately after sizing."

Now, how do you feel about neck tension after bending, flexing, stretching your case neck using the bullet as a lever?

It's a trade-off and you need to decide for yourself which works best for you.

In the grand scheme of LR Hunting, most of us need more range time and less straightening.

-- richard

 

[Bart B]

Now, how do you feel about neck tension after bending, flexing, stretching your case neck using the bullet as a lever?

Good question....

I feel folks might consider sizing their fired cases such that the neck and body stay in alignment as much as possible as the fired case dimensions are changed. And change those dimensions as little as possible

 

[Bart B]

Pressing on a bullet whose case isn't supported anywhere in front of the shoulder-body junction is not a good idea. Especially with lighter neck tension on it.