Got a concentricity gauge

[MartyK2500]

Finally upgraded my concentricity gauge.
Ordered a sinclair's gauge from brownells.
Previous one was a mirror that i'd roll my ammo on, now time to compare both.

Out of a 100 loaded rounds, i'd say in average
1 thou runout 10%
2 thou runout 75%
3 thou runout 10%
4 thou runout 5%

The 3 thou runout was not noticeable on my mirror, at 4 thou i'd start to see a very very slight variance.

What is the aim, i'd imagine 2 thou and under would be alright?
As to why i do have a few 3-4 thou rounds, i don't know.
When i started reloading last year, my pilot for neck turn was too big and made problems. I also had switched from wet tumbling to dry tumbling, witch had given a hard time sizing necks previously.
I wonder if these problems carry on a few firings later, or maybe just something in my process.

I do feel like ordering 300x fresh brass casings for my new barrel though

 

[prairie lover]

4 thou total needle movement? I believe on the Sinclair tool that would mean 2 thou runout.

 

[Paul_T]

You are measuring TIR (Total Indicator Reading) so as above your runout is half that.

 

[MartyK2500]

Yes measuring total needle movement to get to 4 thou


Edit : just double checked the gauges instructions and try to find info online.
If total movement of needle is divided by 2 to calculate runout, i would think my process and dies are doing pretty well

 

[Trinimon]

What brand dies yer using, Marty?

 

[MartyK2500]

.308
Lee single stage press
Redding body die (used every firing)
Lee collet neck die
Forster N/M ultra micrometer bullet seating die

 

[sharp shooter]

Do you measure on the neck or bullet?

 

[MartyK2500]

There are 3 points, as per instructions i had seen.

Rear of casing touches a stopper, so rear rolls on bearings.
1/4'' under shoulders, almost exactly where my annealing line ends, rolls on bearings.
Needle is touching Ogive (marked a round in comparator to adjust first time), with little tension. Dial indicator moves 10 thou when i insert my round, give an idea of tension i have set it at. Which is not enough to push round out on it's own, but at least has a bit of tension.

 

[GreenBob]

What gauge did you buy?

 

[MartyK2500]

Not set up on this pic, picture taken right after unpacking
With this setup, my 85%+ needle movement is 2thous or under

 

[bigedp51]

Food for thought................

You spin the case on the case body to measure neck and bullet runout.

You are full length resizing and the case body does not touch the chamber walls.

The case is supported in the rear by the bolt face and by the bullet in the throat.

I have both runout gauges pictured below and the Hornady gauge reads half of what gauges that spin the case on its body.

Below is from German Salazars website "The Rifleman's Journal" and where I read the statement "The cartridge case should fit the chamber like a rat turd in a violin case" for the first time and understand the full benifits of full length resizing. Meaning giving the cartridge wiggle room to let the bullet be self aligning with the bore.

In the posting below Mr. Salazar is answering a question about "partial full length resizing" and explains the benefits of complete full length resizing.

Reloading: Partial Neck Sizing
by German A. Salazar
http://riflemansjournal.########.com/2010/06/reloading-partial-neck-sizing.html

"Now the last scenario, a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway."

Bottom line the U.S. Military considers ammunition with .003 or less bullet runout to be match grade ammunition.

 

[MartyK2500]

Blog is open to invited reader only...

So from what i read, the hornady will immediately give you your runout reading, the RCBS (which ressembles my sinclairs) you need to divide by two to get your runout.
In the diagram, the top drawing is your hornady and bottom is rcbs.

Right now i am not full lenght resizing, i do have a FLS die though.
Back then i didn't have a concentricity gauge, i had a mirror.
When LEE collet sizing + redding body sizing, i wouldn't see anything wrong in the mirror, when LEE FLS, i would see a tiny bit of movement.

My redding body die will push shoulders back and shrink body a little bit, which gets me to your point of loose casing in chamber.

I am shooting in a savage, since it's my first bolter, i taught they all had swiveling lugs.
Was surprised to see my buddies rem 700 lately with the bolt out, it's one piece no swiveling movement.
Read a bit on it, see like the swivel helps in chamber/cartridge alignment, and is one of the reasons savage is accurate for cheapo.

Of all my loaded rounds, 2 thou has been my worst runout.
The big chunk of them, being 1 thou.
So by military standards i am shooting match ammo.

For the Fclass or long range disciplines, what is the tolerated spec to be considered match?

 

[bigedp51]

When you full length resize you greatly reduce any chance of a warped case effecting bullet alignment. Also your shoulder bump effects a warped case because the base of the case is not 90 degrees to the axis of the bore. Meaning the warped base of the case causes the bullet to tilt in the chamber.

On top of this when neck sizing only you must be careful and keep the rear of your bolt lugs greased to prevent galling the lugs.

When full length resizing and the proper shoulder bump with each loading the ejector pushes the case forward and away from the bolt face. Meaning the rear of the case does not cause the case to tilt because it does not touch the bolt face.

http://www.neconos.com/item/Concentricity-Wall-Thickness-and-Runout-Gauge-12

Concentricity, Wall Thickness and Runout Gauge
The NECO, patented, Case Gauge is the most versatile instrument available for measuring the various accuracy determining factors of cartridge cases, bullets and loaded ammunition. No other gauge can measure all of the following: 1.Banana curvature of case. 2.Wall and neck thickness variations. 3.Case head squareness. 4.Banana curvature and out-of-round shape of individual bullets. 5.Runout of seated bullet. 6.Total runout of loaded cartridge. The "Case Gauge" can be used to measure cartridges from .17 cal to .50BMG by purchasing the appropriate "chord anvil".

Bottom line, full length resizing gives the chambered cartridge "wiggle room" and has much less effect a warped case has on bullet alignment with the axis of the bore.

This alignment effect is more pronounced with larger diameter military chambers where the case warps even more and effects accuracy.

NOTE, this is where using the o-ring method of fire forming your .303 British cases helps greatly. The Enfield bolt face is not recessed and does not center the rear of the case in the chamber and the rear of the case just lays in the bottom of the chamber. And when using the o-ring method when the bolt is closed the o-ring is compressed and it centers the case in the rear of the chamber.

 

[MartyK2500]

I never did and don't plan to ever, neck size only.
Each firing, my cases are body sized like a FLS would do, and set shoulders back 2 thous.
I can imagine since top of casing is not supported, there could be possibly a bit of misalignment when body sizing. Maybe not.
But the wiggle room, i do have it, as my body die reduces body dia all around like a FLS does, and pushes shoulders back.

Interesting concept for this oring method. I do not have that caliber though, for my learning curve, as much in shooting as reloading, i decided to stick to the old and tried 308
That looks like a nice gauge in the link

 

[Sakoman .308]

That is a nice piece of equipment Marty, Congratulations!

 

[MartyK2500]

That is a nice piece of equipment Marty, Congratulations!

Thanks!
Happy to finally be able to measure runout.
I think this was indeed, my last piece of necessary reload equipment.
At this point anything extra is luxury, like the autothrow, which i will cave in for soon enough!

 

[bigedp51]

You may want a good fast neck thickness gauge also when checking case neck runout. If you do not neck turn your brass and measure neck runout you need to know the neck thickness variation to get a true neck runout reading. Meaning subtract the neck thickness variation from your neck runout reading.

Below is a simple and fast reading neck thickness gauge that I use more than my runout gauges.
With one twist of the wrist it gives you neck thickness variations and the uniformity of your brass.

 

[curseyou]

Food for thought................

You spin the case on the case body to measure neck and bullet runout.

You are full length resizing and the case body does not touch the chamber walls.

The case is supported in the rear by the bolt face and by the bullet in the throat.

I have both runout gauges pictured below and the Hornady gauge reads half of what gauges that spin the case on its body.

Below is from German Salazars website "The Rifleman's Journal" and where I read the statement "The cartridge case should fit the chamber like a rat turd in a violin case" for the first time and understand the full benifits of full length resizing. Meaning giving the cartridge wiggle room to let the bullet be self aligning with the bore.

In the posting below Mr. Salazar is answering a question about "partial full length resizing" and explains the benefits of complete full length resizing.

Reloading: Partial Neck Sizing
by German A. Salazar
http://riflemansjournal.########.com/2010/06/reloading-partial-neck-sizing.html

"Now the last scenario, a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway."

Bottom line the U.S. Military considers ammunition with .003 or less bullet runout to be match grade ammunition.

I'm curious. But this reads like an idea, not fact, even from a guy like Salazar. Just like brass fit to chamber by neck sizing gives a tighter, more repeatable fit. Who is to say which is better? We need a box of truth.

It would be helpful if he could load 100 rounds each using neck/bump vs full sizing. Same ammo press powder bullets and rifle and shooter. Then we could evaluate the results based on how they actually impact performance. Then conjecture and theory have a moment in the sun.

Neck sizing wasnt an accuracy thing when I got my dies. It was an attempt to preserve brass life, as it slows brass wear and flow by minimizimg work hardening. You can get a few extra reloads compared to full length sizing.

Salazar sounds like he thinks he is pseudo-headspacing off the ogive. That the bullet will decide its alignment with the throat and not the shoulder in the chamber and the relation to the neck. Has a voodoo feel to it.

 

[Grant Shave]

there are several things that can induce run out on a case.... #1 in my books is cheap shellholders, but can be others ie: do you neck turn for uniformity ? if not maybe you should, whos dies are you using.... price does make a difference here but not always, do you use a standard fl die ? if using a bushing die ? maybe you should not , how much neck tension are you using ?

Lastly, concentric gauges are finicky things and require a great deal of practice to master repeatable measurements, go with what shows on paper.... no harm no foul

 

[liberty]

Unless you're shooting long range it wont matter,,,

if you are, separate them and shoot the higher runnout rounds as foulers or sighters,,