Loaded round concentricity

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  • Last Post 04 August 2016
Pete Voss posted this 07 November 2010

Recently acquired a Hornady concentricity guage largely on the advice of Ric Bowman. This guage has a rubber or nylon tipped screw which bears on the bullet and will supposedly straighten out crooked rounds. I used it on the ammo I had loaded to shoot a match today--actually just the rounds with which I planned to shoot the last (prone slow fire) stage. Well, I had a decent match going with good (for me) scores of 97 in rapid sitting and 93 in rapid prone. The latter was a nice round group of eight shots in the nine and ten rings but two 8's spoiled it. Anyway, I was confident I'd be able to shoot maybe a 90 in the last stage. Alas! My shots were all over the place! I had a miss, two 6's, and various other wild shots to finish with a 61. Virtually none of the shots were on call. Ric--do you think the “corrections” I made may have actually tweaked (read bent) the bullets? I probably should do more testing/tweaking before asking for advice but this was so unnerving and annoying that I couldn't wait. Incidentally, my load was the tried and true 16g of 2400 behind a Saeco 315 cast of 50-50 Lino/range lead.

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tturner53 posted this 07 November 2010

I can't speak to the concentricity gauge, but if you don't mind I'm curious about your load. I assume that's in a M1 Garand? Your rapid prone and sitting scores were purdy darn good in my book, same load as last stage? Is so, maybe something else went screwey. I sure do like that 315.

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Pete Voss posted this 07 November 2010

No, not a Garand. My gun is an '03 Springfield that I “rescued". It had been semi-Bubbaed but the only alteration that couldn't be undone was the installation of a Redfield receiver sight. I had to use the drastic Easy-Off oven cleaner treatment on the cut-down stock and then had it epoxy bedded. It now sports a globe front and the socket for a quick-release front swivel. It's pretty long-throated but the barrel looks good. Yes, my loads for all stages were the same. Next time I'm going to just use the concentricity guage to sort out the best (straightest) rounds for the slow prone and not try to actually correct the crooked ones.

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RicinYakima posted this 07 November 2010

Pete,

I tried the “correcting” theory, but it didn't work well for me either. My bullets were both old WW's plus 2% tin and linotype. I don't know if they bent, or just something bad happened inside the neck. I only shot about five 10 shot groups with them.

After that I didn't fuss with trying to fix them, if they were out more than 0.003", I just but them in the sighter rows of the the 100 round boxes I keep for match ammo. With my best bullets, dies and cases, I can keep about 90% into a group of less than 0.003” That is the point where the rifle doesn't show any difference on run out.

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madsenshooter posted this 19 August 2011

Are you using an M-die to size the necks or at least an expander larger than what you'd use for a jacketed bullet? Makes a world of difference in runout produced. For my Krags I use a 303 British expander, just started loading for the 6x45 and got an M-die as I was seeing a lot of runout on my finished rounds. The M-Die took care of that. I also noted some of my attempts at applying a light roll crimp on the 6x45 pulled the bullets down crookedly because the top band, which was just below the case neck, had a little forward protrusion on the part line. Abandoned the crimp and went from maybe 30% showing visible runout to nearly 0%.

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steveco posted this 19 August 2011

Pushing against the bullet could be adversely affecting neck tension, making it a looser fit in the case neck and hurting ballistic uniformity. This could be the downside to the design of the Hornady tool. FWIW, I have had good results with the trutool (www.trutool-equipment.com). You insert the neck of the loaded round in the proper hole and apply hand pressure to gently straighten the round. Neck tension doesn't change. It's easy to develop a feel for it.

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RicinYakima posted this 19 August 2011

Madsenshooter,

My loading techniques and equipment list were published in The Fouling Shot in the Sept/Oct Issue of 2007, the year I won the scope military rifle nationals. Please refer to that issue.

As a rule of thumb, I have been using the inside neck diameter of the fired case as a starting point and working up from there. You are wise in abandoning the crimping process for accuracy work, as it never helps with cast bullets.

steveco,

My match shooting has been with '03 and 03A3 Springfields for the last 15 years. The biggest challenge is that the chamber is not in line with the bore. My Match 03A3 is 0.003” out from body centerline to bore centerline. Most I have measured are closer to 0.006” out. When I was working with the concentricity concept 10 years ago and shooting up 1000 primers, I found that ammo only has to be a straight as the chamber, i.e. rounds 0.001” and 0.002” didn't shoot any better than ones 0.003” if that was the chamber off set.

This is why I am so opposed to having modern commercial barrels shoot against original barrels. Not that the barrels are so much better, but any backyard gunsmith with a piloted benchrest reamer, can make a rifle that will shoot better than 99.99999% of the military rifles ever made. Don't think so? Just go look at the CMP games with Krieger, Lijla, etc. barrels and custom gunsmithing.

I quit shooting over the chrony and worrying about number years ago for match ammo. What does it do on the target? High ES and SD's are covered up by group size in military rifle groups at 200 yards. It just doesn't matter.

FWIW, Ric

p.s. You both should consider joining the CBA. The Fouling Shot alone is well worth the price of admission, beside getting to shoot postal matches!

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madsenshooter posted this 22 August 2011

Already joined, Jeff just hasn't made the change on the site here. I was asking the OP about his loading procedures. I can see what you mean about chambers being off, on some of my Krag brass. They just are what they are when I load them, can't even roll them to check for visual runout.

Another thought that occurred to me, how to you check concentricity when chances are very good the bullet in the end isn't concentric in itself.  Even Don Eagan's molds don't throw perfect bullets, and they're the best I've encountered so far.

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linoww posted this 23 August 2011

madsenshooter wrote: Another thought that occurred to me, how to you check concentricity when chances are very good the bullet in the end isn't concentric in itself.  Even Don Eagan's molds don't throw perfect bullets, and they're the best I've encountered so far.

I agree with you.Best you can do it check the runout on the neck and compare it to your bullets run-out.

"if it was easy we'd let women do it" don't tell my wife I said that!

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linoww posted this 23 August 2011

"High ES and SD's are covered up by group size in military rifle groups at 200 yards. It just doesn't matter"

My feelings on being too picky on runout mirror you SD ES theory. Try to get plainbase 30's shooting MOA @ 1100-1200 with high SD's it DOES matter.GC's at 1400-1600 dont seem as bothered.

My runout theory with milsurps-

By the time you chamber them in crooked chambers they bend(or self align if you want to be an optimist) however they want anyhow if the  neck tension isn't too much.Try remeasuring a runout checked (indexed @ bad side) round after chambering it Its usually different.Frank Marshall's indexing seems the best to me but I'm to lazy to do it consistently.

George

"if it was easy we'd let women do it" don't tell my wife I said that!

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madsenshooter posted this 23 August 2011

A good example is little 6mm bullet in a round that had a dud primer in it. I've got a 5 groove rifled barrel. I see 3 good rifling imprints, one light one, one missing. The mold was cut with one of Eagan's cherries, you can't see any runout, must be some, but I can't say if it's in the bullet or the loading. I appears one of the lands hit right on the part line and forced the bullet just a tiny fraction out of alignment with the bore. I guess that's why we make them bigger than the bore. I hate odd numbers of grooves, they don't really get along with boreriders unless you fill the dimension from the top of a land to the bottom of the groove across from it. At that point, it isn't really a borerider. Filling that dimension on my Obermeyer would require a .240” nose on a .243” bullet.

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fa38 posted this 29 October 2011

Not an 06 but a Redding Competition Bullet Seating Die for my 40-65 cured most of my cartridge runout problems. With my old dies I had cartridge run out from .003 to .008 and with the Redding die it is never over .003 and usually .002 or less.

It also is a good cure for shaving lead from the bullet on the cartridge mouth.  Easy fast bullet seating.

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TRKakaCatWhisperer posted this 19 December 2011

SOMEDAY I'll modify a set of WILSON seaters for my cast bullets. .002-.003 is typical runout with jacketed. Need the dies to be larger for cast (obviously).

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R. Dupraz posted this 21 December 2011

Pete:

AAH, Concentricity. I won't live long enough to count all the time I've spent trying to get this magical detail right.

First of all, as I understand it, the last stage of the match was where things went south. Were these rounds the only ones that you attempted to straighten and then shot them last or were the straitened rounds mixed in with the rest of your match ammo and fired throughout the match? With that drastic of a change, I wonder if something else was going on during that last stage..

After loading and shooting the 45 X 2.4 in long range BPCR Matches and my Israile K-98 7.62 in the cast bullet matches for several years, the following is what I believe to be true with regard to concentricity. 

I am not familiar with the Hornady gage and straightening tool. But someone is going to have to talk awful hard in order to convince me  that a loaded round that is not concentric can be turned into  match ammo by straightening. Especially when loaded with cast. It has been my experience that if everything else is reasonably concentric and straight, loading press, dies, rifle chamber and bore and bullets, it is the cartridge brass that really  controls the concentricity of the loaded round. If the case is out, whether it be straight wall or bottle neck, trying to bend it back into shape and make consistent match ammo out of it won't work. And there is no amount of bending that is going to make it straight because of the inconsistancy of the brass in the neck  when it was drawn initially. This is why there is match brass and the other kind. Some years ago, I ran across an old article on military match brass and the author talked about this and I have proven it to myself to be true. Trying to make a crooked round into a straight one by bending it more that likely results in a damaged bullet. 

So, back to your post. I would suggest that in order to find out whether or not your loaded rounds are working for you, use you gage to find all with minimum runout, say o to 3 thousands. sort out the others that exceed this and straighted them. Shoot some groups on paper off of a bench and see what happens.

After all that tribe, this is what works for me. Both for the BPCR and my 7.62 cast gun. I use an RCBs concentricity gage to check the necks of the cases. Any that show run-out of more that 3-4 thousand's are segegated. For the K-98 I seat with a Wilson straight line seating die in a drill press and the concentricity is checked again. All round that exceed my limits are shot as sighters and practice The 45 X 2.4 rounds are thumb seated and after loading are not checked again because the bullets are bore riders and I want them to aline themselves as much as possible with the bore after chambering.

I will try to post a couple of match sighter targets that I shot with my K-98 after I started using the above method. These were fired during the match, the 100 yd and 200 yd stage one after the other. Sighters, don't ask about my record targets !! This is the best that my old girl has ever done.

R Dupraz

    

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R. Dupraz posted this 21 December 2011

Those targets again!

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R. Dupraz posted this 21 December 2011

try again

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Ranch Dog posted this 28 December 2011

I find this thread very interesting because of my recent work trying to cure concentricity issues with the short necked 338 Marlin Express with .339 cast bullets. I purchased a Hornady Ammunition Concentricity Gauge and the tool is great for measuring run-out. It does have a limitation, the maximum meplat the tool can accept seems to be .245". I like others in this thread question the value of ammunition that has been straightened with the Hornady tool.

My concern started with the cast bullet loaded ammo in that it was inconsistently difficult to chamber. I knew the bullet diameter and ogive dimensions where perfect based on the bullet being designed for the chamber through a chamber impression. When measured, the run-one the ammunition was running .006” to .009". Unfortunately, correcting the concentricity with the tool actually hurt the performance. Groups with the .009” maximum error where producing 5” to 6” 5-shot groups at 50-yards. Ammo corrected to .015” typically did not hit the target board. If they did, there was evidence that the bullets were tumbling. This was consistent across five five-shot groups of each, corrected and uncorrected.

I'm not questioning the quality of the Hornady tool, as it is built to a very respectable standard, just questioning the wisdom of shooting corrected ammunition.

The run-out I'm experiencing is the result of the quality of my brass. It is brass from “pulled” Hornady ammunition that I purchased from a vendor about a year after the 338ME was introduced. Components were not available but I found the brass and other components available on the internet. I suspect that it is from factory ammunition that had pressure problems. My rifle was one that experienced an overpressure event with the first two shots of the rifle, using factory ammo, seizing the bolt in battery. My pressure trace equipment recorded 65K PSI at the shots. Marlin replaced the rifle and Hornady recalled the ammunition I had bought.

The brass has tooling marks from the bullets being mechanically pulled. The brass was run through a Lee Pacesetter dies, without the expander, as the brass is primed and then reloaded. This is a large lot of brass and I was going to work through it but have since gone back and started working with the once shot brass. The run-out with this group, once loaded is the typical .003". I did correct some with the Hornady tool to .015” and they shot just a miserably as the never fired brass did. I have not shot the uncorrected ammo as that was right before I took a break for Christmas. My concentricity error stems from the bullet pulling on these pull-down cases.

I was looking at this cartridge in that I was going to revise my bullet design but Christmas brought the 2012 Marlin lineup announcement and the 338 Marlin Express has been dropped. I suspect I will drop my effort as well.

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Premod70 posted this 06 June 2016

I work with the case necks and let the bullets fall where they may, using side stress on a lead bullet to improve it's spin is counter-productive. The brass has the strength advantage and a bent lead bullet is all one will get for their efforts to center the spin. I use a Lee collet die followed by a BACO step expander, anneal the brass as needed(that depends on how energetic I feel at the moment) and seat with a common everyday RCBS seater. A habit I have developed when seating a bullet is a light repetative touch of the seater when it first bears against the bullet before I lower the handle of the press, it helps to center the bullet or so I think.

Forrest Gump is my smarter brother.

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beltfed posted this 29 July 2016

Like fa38, I use a good seating die for my '06sA Forster Bench Rest seating die.But I have not checked concentricity of the seated lead bullets.....yetbeltfed/arnie

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onondaga posted this 29 July 2016

You can easily reduce run out in loaded ammo to an inconsequential,  non significant statistic if you are loading for a bolt rifle or single shot with a batch of standard brass and bullets loaded with the Lee Collet Neck Sizing die set and your fire-formed brass.

If you have to turn brass and use odd COALs to accommodate non standard chambers or out of standard loading components, you are welcome to fight with concentricity  forever.

Use decent matched standard brass and bullets in a standard, up to specification bolt rifle or single shot, The Lee Collet Neck Sizing Die set routinely makes ammo with less than .001” run-out or you are simply using the set wrongly. It is lavishly unnecessary to bother to even check concentricity of ammo correctly loaded with this die set.

Gary

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beltfed posted this 29 July 2016

onondaga,I am in fact virtually about to try my Lee Collet neck size die for my '06 brass for my03A1 and 03A3.Will be interestingbeltfed/arnie

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onondaga posted this 30 July 2016

 my Springfield likes Lee Collet Set and my cast bullets sized at .311". The Lee 185-RNGC shoots well.

Gary

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Westhoff posted this 03 August 2016

It's kinda hard to do, but this time I've gotta admit I agree with Gary.

I use Lee collet dies for both my “06 loads and my .300 Win. loads. I usually load in groups of 50 or 60 rounds, and when I get 'em all loaded I'll pick 3 or 4 rounds at random and check concentricity. I just don't find any more than .001” out, and not too many of them.

That's good enough for me!

Wes

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onondaga posted this 04 August 2016

Better

My old O3A3 was built from old new parts including an unfired Barrel. It shoots pretty good,  I'm very happy with it and that Lee 185 round nose shoots the best for me.  I hope you have as much fun with yours as I am having with mine. The rifle just shoots for me and hasn't been fussy at all.  I even got the Ranch Dog 165 flat nose to shoot well, but the Lee bullet shoots better.  the Lee 300 AAC heavy weight also shoots excellently but it is not a hunting bullet  unless you turn unless you turn it around backwards.

Gary

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