concentricity gauge

[BoydAllen]

My point was that I had not considered using a forming die to bump shoulders. The caliber was irrelevant. Also, my remarks about various old military arms was not to say that they do not share anything with more modern designs, but that they are different in some important ways, and it is those differences that should not be use as a guide. On the authority of Mr Hull, no disrespect, but the testing that Sierra, or any bullet manufacturer does for their quality control, is not even in the same ballpark as the finest competition accuracy. Take your rat turd and violin theory to a benchrest match at pretty much any distance that you would like and see how well it works in that situation. Finally I was not disparaging your posts in general. I was, and am disagreeing you in this thread. My agreement on one or more things, has no bearing on whether I will on others. I started out with a Lee Loader, and then progressed to a RCBS one piece FL die set, and while they both worked reasonably well for accomplishing my goals at the time I was using them, we have learned a thing or two since then. I have four different concentricity gauges, and have tried pretty much all of the rest. Given that experience, I do not want one that supports the back of the case on the rim, or extractor groove. or which requires an inordinate amount of force to turn a case.

 

[JRS]

I now use the model made by 21st Century. It is the Sheeeeeeeeetz

 

[hotrodlouie]

This checks run-out and straightens run-out. I find run-out is at the tip, bullet starts cocked? I use a wood dowel and 4oz. hammer and lightly tap the tip. The indicator reads the low side so you can move the tip half total run-out and watch movement and know when to stop, no guesting. Most of my run-out is .001-.003 at the tip when need to correct any run-out.
This is my 2.

 

[mikecr]

+1 VaniB
Don't bend necks, make straight loaded ammo as confirmed off bullets on v-block runout gage(Sinclair).
I know Sinclair merchandises it as a concentricity gage, it's not. It's a runout gage, like bobm's, which is really nice.

 

[sbhooper]

I just bought the Hornady gauge and I thought that it was easy to set up and easy to use. I had no problem getting the ammo that I tried back into the Hornady-recommended specs.

 

[mikecr]

hotrodlouie/sbhooper, until you've compared your results with similar gages linked, you don't know what you really have for straight ammo.
http://www.sinclairintl.com/reloading-equipment/measuring-tools/concentricity-gauges/sinclair-concentricity-gauge-prod37479.aspx
or;
http://www.sinclairintl.com/reloading-equipment/measuring-tools/concentricity-gauges/neco-concentricity-gage-prod39500.aspx
or, the best I've seen;
http://www.accurateshooter.com/gear-reviews/new-wheel-drive-concentricity-gauge/

 

[Bart B.]

The picture in reply 8 showing how a bottleneck case shoulder against the chamber shoulder and the case neck well centered on it from firing pin impact and clearance around the neck to the chamber neck it interesting. I think it would also show, if so pictured, that the case body behind the body-shoulder juncture doesn't touch the chamber at all; there's typically a thousandth or more clearance at that point, too. And the only part of the case body that touches anything is back at the pressure ring where it's pushed against the chamber by the extractor pushing on the case head. All of which to me means, the case axis is at a very small angle off the chamber axis and for every .001" off chamber axis the case pressure ring is, a perfectly straight cartridge will have its bullet tip about .0005" off the throat axis. Virtually all cases are not perfectly round right behind their shoulder and whatever out-of-round the case is at that point, it'll be transferred to the bullet plus some extra amount.

I think bullet runout on cartridges should be measured relative to how the case fits the chamber when fired. None of them made today uses the case shoulder as the front reference. They all use the case body behind the shoulder, the whole body between shoulder and pressure ring, or someplace on the bullet. But the pressure ring at the back end of the case is OK for the back reference as it's against the chamber when the round fires. All of which is why I usually put the case shoulder in a V block as the front reference.

 

[rwk]

Has anyone made there own tool.

 

[fguffey]

Has anyone made there own tool.

Yes, I use tools that are not on the reloaders approved list and I have made them. Problem, when explaining how they work it can not be talked to death, for simplicity reasons. Then there are case length gages. Great for sorting cases by length.

F. Guffey

 

[Bart B.]

Boyd, regarding your remarks:

On the authority of Mr Hull, no disrespect, but the testing that Sierra, or any bullet manufacturer does for their quality control, is not even in the same ballpark as the finest competition accuracy. Take your rat turd and violin theory to a benchrest match at pretty much any distance that you would like and see how well it works in that situation.

What do you think is the accuracy that happens when ammo is reloaded to Jim Hulls method with full length sized unprepped cases and the best bullets in SAAMI spec chambers at 100, 200, 600, 800 and 1000 yard ten to twenty shot groups?

 

[mikecr]

In the short term, I'm convinced that better ammo shoots at least as well as crappy ammo.
In the long term, I'm positive better ammo wins.

 

[Bart B.]

bigedp51, your comment:

On a Mauser type bolt action the cartridge is centered in the rear by the bolt face and the claw extractor holds the case against the bolt face.

With all of the Mauser style extractors on the rifles I've shot, there's enough clearance between the bolt face and extractor claw to let cartridges loaded from the magazine to let their rims easily slide up into that space. With a round held in the bolt face and chambered, there's a few thousandths clearance between the case head and bolt face as I've measured it. And all the bolt face diameters are much larger than the chamber at the breech end so there's no way they will center the case.

Firing empty primed cases so chambered slam against the chamber shoulder hard enough to set the case shoulder back a few thousandths. None of those extractors held a case head against the bolt face. But they did push the case against the chamber wall opposite the extractor claw.

Where does the reward force on a Mauser style external extractor come from that would pull a chambered case head against the bolt face?

 

[bigedp51]

Bart B.

I guess I look at the world differently than you do and the ejector button causes more misalignment and pushes the case away from the bolt face.

And the claw extractor does hold the case against the bolt face.

So big old beefy claw extractors can even solve "Headspace Maximus" problems or do you think the shoulder of the case stopped forward movement. :

Now go snap a few of your cartridge cases under a good claw extractor that isn't worn out and see how tightly they hold the case against the bolt face.

 

[Bart B.]

Looks to me like those claw extractors are pushing the case rim against the bolt shroud opposite the extractor claw. All my controlled-feed classic Win 70's do that and there's light between the bolt face and case head.

The in-line ejectors in my push-feed Winchester and Paramount actions push the cartridge case full forward in the chamber so the shoulder stops against the chamber shoulder.

In measuring an aluminum rod resting on the inside of a chambered case head (with .003" head clearance in that chamber) and the unsprung firing pin in the cocked position, the end of that rod at the muzzle will move out .003" on a dial indicator as the firing pin's pushed against the primer in the case. No part of the extractor keeps the case head against the bolt face as it's easy to push the firing pin .003" forward pushing the case shoulder into the chamber shoulder.

I have fired empty primed cases with brand spankin' new extractors in Win 70s and all of them had enough rim clearance to let .308 Win case shoulders get set back a few thousandths.

 

[sbhooper]

hotrodlouie/sbhooper, until you've compared your results with similar gages linked, you don't know what you really have for straight ammo.
http://www.sinclairintl.com/reloading-equipment/measuring-tools/concentricity-gauges/sinclair-concentricity-gauge-prod37479.aspx
or;
http://www.sinclairintl.com/reloading-equipment/measuring-tools/concentricity-gauges/neco-concentricity-gage-prod39500.aspx
or, the best I've seen;
http://www.accurateshooter.com/gear-reviews/new-wheel-drive-concentricity-gauge/

I realize that, but I am not going to invest a whole bunch of money in stuff to split hairs. I have reloaded for over 40 years and never used one before. My ammo has always been sub-minute or even half-minute depending on the dies and rifle. This was more of an experiment to me.

If you have used these a lot, what is the difference in accuracy between, say, a .002 and a round that measures .008? I am just trying to figure out if this is just an expensive toy, or really has merit for my hunting loads.

 

[BoydAllen]

If you are happy with the accuracy you are getting, it would be a toy....but then most of the shooting stuff that I have could be classified as such. I think that the best use of concentrecity gauges is to evaluate your dies. Over the years I have checked and found satisfactory ammunition loaded by several friends, and some that needed a change in the process. Do you know anyone with one? If you do, take some of your loads of each caliber, to his house and check them out. I can tell you how to load straighter, or that your process is good to go as is. I just like having the tools to measure things for myself. When there is no shooting to be done, I can do a few experiments and take a look at the results. This isn't rocket science. There are some things that are pretty well known to work better than others, and the reasons that they do are pretty straightforward.

 

[bigedp51]

Looks to me like those claw extractors are pushing the case rim against the bolt shroud opposite the extractor claw. All my controlled-feed classic Win 70's do that and there's light between the bolt face and case head.

The in-line ejectors in my push-feed Winchester and Paramount actions push the cartridge case full forward in the chamber so the shoulder stops against the chamber shoulder.

In measuring an aluminum rod resting on the inside of a chambered case head (with .003" head clearance in that chamber) and the unsprung firing pin in the cocked position, the end of that rod at the muzzle will move out .003" on a dial indicator as the firing pin's pushed against the primer in the case. No part of the extractor keeps the case head against the bolt face as it's easy to push the firing pin .003" forward pushing the case shoulder into the chamber shoulder.

I have fired empty primed cases with brand spankin' new extractors in Win 70s and all of them had enough rim clearance to let .308 Win case shoulders get set back a few thousandths.

And if you owned a real Mauser action instead of one made by U.S. Repeating Arms that just uses Winchesters name and cost saving methods used in it construction you might then know what your were talking about. What you have is a imitation of a real Mauser claw extractor and shows how much you do not know about the subject.

If you had ever pushed and "snapped" a cartridge case under a real Mauser claw extractor then you would have NEVER posted your first comments about claw extractors.
Meaning your experience is limited to one American made rifle and not real Mauser actions, you can't win this one sided discussion, every milsurp Mauser type action I have holds the case "FIRMLY" against the bolt face. And your mock Winchester is a sales gimmick to promote sales and is like eating mock crab cakes and it just ain't the same thing.

P.S. I have standard concentricity gauge and the Hornady concentricity gauge and using both confirms my decision to full length resize my cases and reduce the cases influences on misalignment with the bore. Because so much can go wrong with your brass after it is fired and resized as shown below.

 

[Bart B.]

Here’s a pre-‘64 Win 70 bolt head showing a brand new, never used extractor holding a .308 Win. case in two views. Note the extractor’s ring that fits in a groove around the bolt head; it limits the back and forth travel to only a couple thousandths. The extractor claw is fixed about .070" away from the bolt face.

Picture on the left shows the case head against the bolt face. Note the .018" clearance to the claw’s back side from the .052" thick case rim.

Picture on the right shows the case head full forward from firing pin impact (if headspace was long enough to allow it) and the rim’s against the claw’s back side.

Note the difference in extractor groove height above the claw’s beveled front edge in each picture. That extractor is quite well fixed in place. If that case has a .004" head clearance in a chamber, it’ll be .004" off the bolt face when its shoulder stops against the chamber shoulder. Should the case shoulder set back .003" from firing pin impact (I’ve measured that much and more), the case head will be .007" away from the bolt face. And the front of the rim will be .012" back from the claw’s back side that grabs the rim to extract the case.

My commercial Oberndorf Mauser double set trigger sporter in 8x57 abd DWM M1909 7.65mm Argentine sporter Mauser both let case rims slide easily behind their claws. And both would allow shoulder setback on primed cases with a couple thousandths head clearance fired with normal firing pin strength. Their extractors did not hold case heads against their bolt faces. Same thing with an FN single shot Mauser magnum and box magazine 7x57 sporter. There was little space between the bolt faces and case heads as the extractors pressed cases against the shroud opposite it where the ejector pushed empties off the bolt face.

You're making too many assumptions about what I've observed and done.

 

[bigedp51]

You're making too many assumptions about what I've observed and done.

It's what you haven't observed and haven't done that is in question, and your posting photos of a Winchester rifle that you apparently replaced the claw extractor on. And all your photo shows is your extractor isn't a very good fit, and any rifle I have ever owned if you dry fire a case will push the shoulder back to some degree. And this depends on case annealing and the firing pin and spring.

And I have also owned Mausers with far, far less clearance than what you have pictured and you have proved nothing, especially using a replacement extractor. We will continue to disagree as you as yet haven't proved anything. :

If you want to start a separate posting called "Measure your rim thickness and extractor clearance then go ahead. But none of this has anything to do with the merits of neck sizing vs full length resizing and what type concentricity gauge you have. But then I have both type gauges because I'm very good looking, brilliant and modest to boot.

 

[sbhooper]

If you are happy with the accuracy you are getting, it would be a toy....but then most of the shooting stuff that I have could be classified as such. I think that the best use of concentrecity gauges is to evaluate your dies. Over the years I have checked and found satisfactory ammunition loaded by several friends, and some that needed a change in the process. Do you know anyone with one? If you do, take some of your loads of each caliber, to his house and check them out. I can tell you how to load straighter, or that your process is good to go as is. I just like having the tools to measure things for myself. When there is no shooting to be done, I can do a few experiments and take a look at the results. This isn't rocket science. There are some things that are pretty well known to work better than others, and the reasons that they do are pretty straightforward.

Well stated. I had .308 stuff that was anywhere from .001-.008. It was produced on some old C-H dies, I believe. It shoots pretty good through my Model 600, which is not an easy rifle to shoot because it weighs nothing. It will be interesting to see if I see a difference since I straightened the ammo.

My 7 mag ammo was very good. Only a couple out of the 20 or so that I checked, needed straightening and it was not by much. RCBS dies were used. This ammo has shot 1/4-1/2 minute in two rifles and so this is definitely splitting hairs.

It is fun to use the tool and check the stuff, though.