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What is runout?

6ShotsOr5?

6ShotsOr5?

NBRSA TSRA NRA
Gold $$ Contributor
New reloader. This is pretty basic, so trolls and know-it-all’s please sit this one out okay?

Saw a thread “GAWD DANG RUNOUT! is it my redding dies?” Don’t know what runout is but I found a lot of threads about how to fix it, and I saw case neck runout and also bullet runout mentioned so maybe there is more than one type of runout? I couldn’t find anything that explained what it is, and I’ve also read several reloading manuals per advice on this forum. Can one of you knowledgeable and helpful gentlemen (i.e. non-troll) please explain what bullet runout and case neck runout are, or provide references to good definitions? PMs welcomed if you’d rather avoid the troll wars today.
 
I think the NECO case gage gives good instructions on different runouts and how to find them. maybe you could get a copy online or request it from neco. unless youre looking for benchrest accuracy and have the tools to get there its not anything to concern yourself with (if youre shooting 1+" groups improving your runout is not your next checklist item in other words)
 
Are you familiar with the tool called "Concentricity Stand" & Gauge ??
There are several on the market, once you see& understand "How" this tool is used it becomes pretty evident what "Run-Out" is.

- Run-Out can be caused from several different things including a chamber that is not correctly cut, which IMO is a worst case scenario & the most expensive to correct.

- Ron -
 
runout is how much the neck of your brass or bullet in a loaded round are out of round with the case body.

you can easily see it in a loaded round just by rolling the case on a flat surface and seeing how much the bullet tip wobbles

many tools made to measure it. the fix is in your reloading procedure not some bullet straightening tool.
 
You can find the answer on You Tube.

At least that where I found an explanation, but I'm a bit more visual than some.
 
concentricity gauge = down the rabbit hole: "interested in something to the point of distraction—usually by accident, and usually to a degree that the subject in question might not seem to merit.”
 
lawman29 said:
concentricity gauge = down the rabbit hole: "interested in something to the point of distraction—usually by accident, and usually to a degree that the subject in question might not seem to merit.”
Click to expand...

Negative !! - This is a Tool that obviously you do Not understand. - There is No magic or "Rabbit holes" and your post seems to be a point of distraction to the topic.
 
Runout is officially defined for use in the USA by ASME Y14.5M.
"Geometric Dimensioning and Tolerancing".

The previous title of this document was ANSI Y14.5.

ANSI = American National Standards Institute.
ASME = American Society of Mechanical Engineers.
 
The way reloaders use the term is in one of two ways, neither of which is strictly correct, but are nonetheless understandable:

1) concentricity. Is the bullet’s bearing surface or the outside of the neck concentric with the rest of the case?

2) straightness. Is the axis of the bullet colinnear with the axis of the case?

Yes, these are both difficult to define and measure on real objects (as opposed to drawings), but the gages get it pretty good. They can point out gross problems at least.

Honestly though, it doesn’t matter unless it’s *really* bad.
 
Last edited:
damoncali said:
The way reloaders use the term is in one of two ways:

1) concentricity. Is the bullet’s bearing surface or the outside of the neck concentric with the rest of the case?

2) straightness. Is the axis of the bullet colinnear with the axis of the case?

Yes, these are both difficult to define and measure on real objects (as opposed to drawings), but the gages get it pretty good. They can point out gross problems at least.

Honestly though, it doesn’t matter unless it’s *really* bad.
Click to expand...

that really depends. with my bench guns culling by concentricity does make a difference. for the average shooter .003 or less will not be noticeably.

two different tools to measure with. each will give you different.results. one measures by supporting the case and measuring the neck or bullet runout at your.chosen spot. one is supported at the base and tip of the bullet or the neck and you measure at your chosen spot.

all depends on how far down the rabbit hole you want to go.
 
Richard Coody said:
that really depends. with my bench guns culling by concentricity does make a difference. for the average shooter .003 or less will not be noticeably.

two different tools to measure with. each will give you different.results. one measures by supporting the case and measuring the neck or bullet runout at your.chosen spot. one is supported at the base and tip of the bullet or the neck and you measure at your chosen spot.

all depends on how far down the rabbit hole you want to go.
Click to expand...
Check out youtube (shaft run out)
 
With reloading, eccentricity and runout are completely different things.
And yes, folks muddle this up.
For instance, the Sinclair concentricity gauge pictured earlier is not. It's a runout gauge.
Concentricity is a quality of centerline, measured as eccentricity from a center, which is never established with and doesn't matter to total indicated runout (TIR).
I refer to actual concentricity gauges as neck-benders, as they're often merchandised for straightening of loaded ammo. Hogwash...

Concentric ammo can still be high in TIR, and crooked as hell w/resp to chambering.
On the flip side, straight ammo is low in TIR, and therefore concentric as well.
Your ammo is not straight until it can read low in runout on a v-block type gauge (similar to that Sinclair).
Don't try to read runout on a neck bender (it will produce a laughably false/low reading).
 
If you support a case or loaded round at two points and put an indicator on a third, the runout, or more properly TID (total indicated runout) is the difference between the highest and lowest reading that you see during a complete rotation of the case or loaded rounds on its supports. In shooting, concentricity refers to how straight a loaded round is. We have various gauges to measure it. some support the thing being measured differently than others, and that has an effect on the magnitude of the TIR that a given case or round will have. This does not mean that one is better or superior to another, but it does mean that if you are having a discussion that those involved will have better understanding if it is known what tool was used to take the measurements. Here is an excellent selection of examples.
https://www.google.com/search?q=con...hUFS6wKHd0PCFoQ_AUoAnoECAAQBA&biw=870&bih=520
 
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