Can indexing bullets improve groups

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  • Last Post 25 February 2015
John Alexander posted this 12 February 2015 

           

    Indexing is certainly useful for telling which bullets came from which cavity when the cavities aren't alike.  It is at least conceivable that in certain cases with really bad bullets that indexing may help shrink groups.  But a lot of good shooters don't index bullets and win without doing it.      Does anybody know of any systematic studies that give information on how bad (and in what way) a bullet has to be before indexing will show a measurable decrease in average group size?    Is it instead just one of those things we blindly do because we read somewhere that it works. Or maybe do in the hope that the more trouble and time we take to reload groups will magically improve.    My own tests were with bullets from a single cavity mold that was beagled out of round and in which the halves were offset more than .001".  These defects made me think that indexing would help. The bullets were shot in a falling block rifle so I could easily and precisely index bullets. I shot a lot of groups but could detect no difference in average group size compared with not indexing.    However, that was with one bullet design (similar to NOE 22570 RN) and in a rifle only capable of averaging about 1MOA for five shot groups.  With different or worse bullet defects, or with other bullet designs, or at higher levels of precision, results might be different -- but do we know?    Maybe we should try to find out.    John

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OU812 posted this 12 February 2015

Maybe hard alloys benefit most by indexing. Softer alloys not so much?

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Bud Hyett posted this 12 February 2015

A half century or more ago, Norma published a study on jacketed bullets, their 6.5 mm 139 grain match bullet, where they altered the nose and base to see what impact this alteration would have. Expectedly, any alteration to the nose or meplat was of negligible impact and any alteration to the base immediately increased group size. If I remember correctly, this was a short article in the American Rifleman. They made cuts in the base and indexed the bullets, they cut the nose off at diagonal angles, the made cuts on the meplat, it was an interesting experiment to read about. If I recall correctly, they used ten-shot groups for the standard of comparison. While a jacketed bullet, the results would be similar with cast. Norma chose this bullet since it was a recognized match bullet. In the late 1950's, this bullet was one of the best match bullets. They shot the altered bullets without indexing to see if that was an influence. Norma indexed the bullets and found the bullets were predictable as to impact. This indexing was at 90 degree intervals and the bullets impacted in the same area relative to the cut both in base and meplat. Their conclusion was that any irregularity was an influence on group size. The irregularity in the nose and meplat area was less than an irregularity on the base. The indexing did help reduce group size, but was not a cure. While hardly surprising to a dedicated cast bullet shooter, this was an interesting article and caused much discussion at the range bull sessions. 

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 12 February 2015

WOW! “A half Century or more” sure sounds a lot longer ago than “before I was drafted". Remember the article and controversy pretty well, but most folks forgot it almost as long ago.

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tomme boy posted this 12 February 2015

Only going to matter if your chamber is not true to the bore.

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joeb33050 posted this 12 February 2015

No, of course not!

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John Alexander posted this 14 February 2015

OU812 wrote: Maybe hard alloys benefit most by indexing. Softer alloys not so much? Maybe.  But who knows? Nobody knows, because we haven't done the work to find out. It is easier just to believe the old husband's tales passed down to us.  Sixty years after Col. Harrison published his attempts to find out what makes cast bullets work, or not work and got some answers (even though some of them were wrong) we still don't know some of the basic things we need to know in order to improve cast bullet groups.   Bud and Norma are right a known substantial defect like bases not square to the long axis of the bullet or a hole drilled into one side of the bullet degrade accuracy and if you know where the defect is you can index it the same for each shot you can get better groups. Several experimenters probably starting with Mann have done it. But it is hard to see how that could that possible apply to real bullets where gas checks are sometime less than square with the axis but bear no relationship with the parting line on the bullet.  We fear internal bubbles but there is no chance that indexing will help because the bubbles are randomly placed if there at all.  If indexing does help why haven't we had a good test to prove it.  Maybe Joe has done one he seems pretty certain.

John   

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Maven posted this 14 February 2015

Frank Marshall said it made a difference in a “Speaking Frankly” column reproduced in Lyman's “Cast Bullet Handbook, 3rd. Ed.”  He even provided targets:  indexing v. no indexing accuracy.

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John Alexander posted this 14 February 2015

What page is that article on?  I have the 3rd edition but got sidetracked by a couple of other Marshall articles.

You are right the late Frank Marshall, one of my favorite gun writers, said it made a difference.  So have a lot of other shooters.

Marshall didn't just give his opinion but also reported on tests that he had done that showed fantastic improvements by both indexing and sorting by weight.  Probably his most widely read article starts on page 140 of the NRA publication “Cast Bullets” edited by Col. Harrison.  I would urge any interested cast bullet shooter to read Marshall's article and then go back and read it again and compare his reported results to your own experience. there are several things in he article that are quite amazing. I will only mention a couple of his results that caught my eye.

Bullets visually OK but not indexed and not sorted by weight produced groups 4.3 times as big as those by bullets indexed and sorted to .1 grain variation in weight.  

Bullets visually OK and indexed and sorted to .5 grain weight variation (two tenths of one percent) variation on the 219 gr. 211284) produced groups 2.3 times as big as the same bullets indexed and sorted to .1grain variation (four one hundredths of one percent.)

I have done similar tests and have never been able to see ANY improvements by either indexing or sorting by weight.   I suppose one possibility is that Marshall tested a really bad batch of bullets. There may be other explanations. 

John

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Maven posted this 15 February 2015

Sorry John, but I can't give you a  page no. as I'm 1,500 mi. from home...in sunny Fla. (I think you can guess why!) ;)

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joeb33050 posted this 15 February 2015

Cut a “V” on the rim or base of the case.

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RicinYakima posted this 15 February 2015

I can not find it in the Lyman book, however it is reproduced on page 140 of Harrison's “Cast Bullets” published by the NRA.

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joeb33050 posted this 15 February 2015

Put a dent in the mold so the bullet has a dot.

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joeb33050 posted this 15 February 2015

Put the V or the dot or both at 12 o'clock in the chamber, and shoot a lot of shots with dot or V or both or none aligned.Measure the groups.See that there's no discernible difference in group size. Note that at least some times in bolt guns the ctg case with bullet rotates as the bolt closes. To align anything in bolt guns the ctg must be forced in the chamber until refusal, then bolt-preferably without extractor, is closed. Even then you're never sure the ctg didn't rotate as bolt closed. I've tested with a 30-30 Martini bench gun, a 32-40 high wall with bresein barrel owned by Ken Hall, a Hepburn 30-30 with bud welsh barrel, Schoyen Ballard in 32-40 and Peterson Ballard in 38-55. It's just another fairy tale, alignment changes nothing.  I've NEVER read a credible report of alignment of bullet, case or both increasing accuracy.

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John Alexander posted this 15 February 2015

RicinYakima wrote: I can not find it in the Lyman book, however it is reproduced on page 140 of Harrison's “Cast Bullets” published by the NRA.

Thanks Ric.  Yup, that's the version I was quoting from --  one of the bibles of cast bullet wisdom. I wonder how many thousands of hours of useless labor that article has inspired?  John

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John Alexander posted this 15 February 2015

Joe,

Thanks for the summation of your testing the effectiveness of indexing.  I withdraw my comment in my post #7 that “nobody knows.”  I guess I should finish reading the latest edition of your book -- or maybe it's just the memory thing.

Maybe everybody has figured this out and nobody is still indexing.  If some shooters are, I wonder if they have test data to support the practice.  How about folks shooting aggregates close to .5 MOA?  Can a positive effect be shown at that level of precision?

I know indexing can be shown to improve groups with big artificially manufactured flaws. But does it ever help with actual cast bullets not deliberately damaged?

John

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TRKakaCatWhisperer posted this 15 February 2015

John Alexander wrote: I know indexing can be shown to improve groups with big artificially manufactured flaws. But does it ever help with actual cast bullets not deliberately damaged?
Agree (first part).  Mann's volume documents it well.  So the question is (cast bullets not deliberately damaged) what unseen defects are there?  Where do these defects occur in the bullet and how REPEATABLE are they in size and/or location? Now we're talking about a level of precision of casting (and other operations of bullet preparation). I would ASSUME that some level of precision is gained by bumping/swaging and other processes.  My assumption is that there are some measurable benefits in the reduction of variations that affect accuracy.  Are these improvements so small that NO ONE has been able to measure and document them?  Perhaps, perhaps not. This raises the question of techniques of measurement.  There certainly are other measurement techniques of precision of anything manufactured.  Most of these are well beyond the capabilities of most all of us.  (I would love to take several hundred bullets  into work and check each one with the CMM.) Mann published a picture of a device to spin each bullet and to observe it's level of instability/stability when spinning on it's nose.  He discovered that a void could be found by that technique.  Certainly it stands to reason that a bullet if unstable in it's spinning would be less accurate that those that are stable. There is room for more good research here.

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TRKakaCatWhisperer posted this 16 February 2015

Hmmm.  There is an obvious advantage to indexing bullets that are not aligned in the case.  Measuring is straightforward, supporting the case in a number of ways (just observe the different styles of Sinclair gauges) and using a dial indicator.  Both sorting for smaller amounts of run-out and by indexing the round; again see Mann's volume. This gets back then to the original question of indexing JUST the bullet.  One simple method of indexing just the bullet would be to breech-seat and study the results.  Easy enough if you breech-seat.  

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joeb33050 posted this 16 February 2015

TRK wrote: Hmmm.  There is an obvious advantage to indexing bullets that are not aligned in the case.  Measuring is straightforward, supporting the case in a number of ways (just observe the different styles of Sinclair gauges) and using a dial indicator.  Both sorting for smaller amounts of run-out and by indexing the round; again see Mann's volume. This gets back then to the original question of indexing JUST the bullet.  One simple method of indexing just the bullet would be to breech-seat and study the results.  Easy enough if you breech-seat.   "There is an obvious advantage to indexing bullets that are not aligned in the case." Maybe a theoretical advantage, obvious to theorists, but I never found an advantage breech seating. Or read of experimental results showing one. "Measuring is straightforward, supporting the case in a number of ways (just observe the different styles of Sinclair gauges) and using a dial indicator.  Both sorting for smaller amounts of run-out and by indexing the round; again see Mann's volume."This seems to be about coaxial cartridges and measurements of concentricity. Pounded into dust elsewhere. Where in his book do you find Mann's talk about runout and indexing? "This gets back then to the original question of indexing JUST the bullet.  One simple method of indexing just the bullet would be to breech-seat and study the results.  Easy enough if you breech-seat."I did breech seat, in SS rifles, as described, and never found any relationship between indexing and accuracy-nor have I ever read a credible report of such.

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TRKakaCatWhisperer posted this 16 February 2015

I'm not ARGUING here.  Simply pointing out issues and aspects of the topic at hand. I look to those people that HAVE found success.  Just not finding nor recognizing it is not good enough.  MEASURE the effect and publish it.  The first step is clarification; research follows.  

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John Alexander posted this 16 February 2015

TRK wrote: MEASURE the effect and publish it.  The first step is clarification; research follows. Amen!  That's what we don't do much of.  We are going to have to begin doing that again just as the folks who got us to where we are did in the 70s and 80s (Ardito and others at that time.) -- but only if we want to improve.  Those who are satisfied with what we can do now of course won't be interested and that is OK too.  They may have as much fun but they won't learn anything new.    The other thing that would help would be put into practice what we do know instead of just doing the same thing more precisely. I wrote an article four years ago (TFS #213) showing that bullets with big gnarly wrinkles shot just as well as “perfect” ones at the .8 MOA level of precision. 

But we still have “serious people” advocating examining bullets with a magnifying glass and remelting bullets with tiny wrinkles all without offering one bit of test results showing that it does any good - just their uninformed opinion.  But, especially if it's in print, some folks will buy a magnifying glass. Cast bullet shooter's critical reading skills seem no better than the general public's.

Just trying to be more precise with our casting and loading procedures ain't doing the job as Joe's compilation of groups at the CBA nationals show.

John

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cheatermk3 posted this 16 February 2015

Joeb33050: “Cut a “V” on the rim or base of the case."

How did you decide where the V should be on the case?

I Try to find the thinnest portion of the case wall and mark it with a small cut,  This is done for all cases in any lot.

Surely, just having an indexing mark randomly on your cases serves no useful purpose?

I then turn the necks just enough to remove the “high spots".  If I've gotten this right, the notch will be aligned with the portion of the neck that has not been touched by the cutter.  After several cycles of loading/firing the material in the thick side can migrate up to the neck, but until that happens I have a case that is the best platform for aligning the centerline of the cartridge, bullet, case assembly with the centerline of the bore.

No?

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John Alexander posted this 17 February 2015

cheatermk3 wrote: I Try to find the thinnest portion of the case wall and mark it with a small cut,  This is done for all cases in any lot.

I assume by your wording that you are talking about the thinnest portion of the case wall inside the body of the case not just the neck. I know this is a practice of some jacketed BR shooters.

After finding the thin side and marking it with a cut in the rim, have you ever shot a test of a series of alternate groups with the case indexed in one orientation (say 12 o'clock) versus identical loads with the index mark randomly positioned (around the clock so to speak) to measure the benefit indexing cases by the thin side? 

If carefully done with enough pairs of alternate groups fired, the results of such a test would would make a great Fouling Shot article and would be valuable information in assessing the benefits, if any, of the practice.

John

 

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R. Dupraz posted this 17 February 2015

I remember reading an article in some publication many years ago that dealt with case orientation in the chamber of a rifle and how it relates to accuracy. Sure wished I could recall where it was because I would like to read it again. Not sure whether the rifle was fired from a machine rest or not but it could have been.    Anyway, I think the rifle was a center fire single shot and the author used a single case, reloading at the bench. He notched the case rim and the first shot at 100 yds was fired with the notch oriented at 12:00 in the chamber. Each successive round was chambered with the notch rotated to the left of 12:00 few degrees more each time   I recall that the included photo of the group was quite revealing. After several shots were fired, rotating the case a little more for each shot, the group was almost a perfect arc from 12:00 to about 8:00.

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John Alexander posted this 17 February 2015

That would be an interesting article to see.  I wish I hadn't given my 25 years worth of Precision Shooting away.  It might have been in one of them.  There was a great flurry of comment for awhile in PS about the idea and the tools to measure it with.  I was skeptical at the time and should have remembered if it was in PS and the defect in the case tested was about case wall thickness -- but then I should have remembered a lot of things.

John

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R. Dupraz posted this 17 February 2015

I “think” that this article may have been in either the Handloader or Rifle magazine. While I subscribed to various gun and outdoor mags. over the years, I never did to either of those. But just bought an issue every once in a while.

I sure would like to see it again. Maybe someone else on the forum recalls the article or where it was.

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joeb33050 posted this 17 February 2015

Fortunately for us all I’ve been tutoring a lady who is taking Statistics 2, and I’ve been working hard to stay just a few pages ahead of her. I’ve been strongly emphasizing the importance of precisely defining/stating the hypothesis that’s under discussion.

I’ve read John’s original post a dozen times, trying to understand the question/s; here’s what I think he wants to know:

 

(Indexing, here, means that the item is oriented in a certain way, axially.)

 

Does indexing imperfect bullets reduce group size?

 

What is the type and magnitude of bullet imperfection threshold where group size reduction begins?

 

Now these imply that that accuracy increases happen when imperfect bullets with varying types and magnitude of imperfection are indexed, and I don’t know why anyone would suspect that this would be the case.

 

It implies, for example, that as base-to-long-axis perpendicularity varies from 90 degrees, that as the smaller angle approaches some number, indexing bullets reduces group size.  Example still: as the smaller angle reaches 84 degrees indexing reduces group size 10 percent.

 

I don’t know why this question, nor how to test the premise.

 

There is another question that might be of interest and more easily tested:

 

Does indexing bullets, cases, or both reduce group size?

 

We could combine the three in the design of the experiment, thus:

 

 Shoot n r groups with cases and bullets oriented randomly

 

Shoot n b groups with the bullet indexed and the case oriented randomly.

 

Shoot n c groups with the bullet oriented randomly and the case indexed.

 

Shoot n bc with both bullet and case indexed.

 

Compare group sizes.

 

We must keep in mind that indexing anything by eye and hand is not an extremely  precise matter. Keeping a dot on a bullet aligned with a v in a case rim, and the v on the case rim aligned with 12 o’clock in the rifle chamber is a process frought with opportunity for error. Keep in mind that on a clock with hands, one minute = 6 degrees. A guess is that alignment of that v is possible with a precision of +/- 6 degrees.

 

So this might be on the way to designing the experiment to test the hypothesis that alignment reduces group size. 

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LWesthoff posted this 17 February 2015

I don't know whether indexing/orienting can be shown to help accuracy - but I do it, and here's why: Nothing can be made perfectly. If there are imperfections in my rifle's chamber, in my bullet mold, in my sizing die and/or in my seating die, then if when I am casting, sizing, seating and chambering I always orient everything in the same way (as precisely as I am able) when I am testing for an accurate load, and then when, after choosing a load, I shoot it in competition, I figure I have something that works in MY RIFLE, machining errors notwithstanding.

I have neither the time nor the money to test all these things to see which ones do, and do not - affect accuracy. so I try to always do each thing the same way every time. Then when I find something that works, I can do it again.

Makes sense to me.

Wes

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Ken Campbell Iowa posted this 18 February 2015

creighten audette american rifleman june 81.

benchresters do not always agree on this result; however most will prefer the most consistent brass available; usually lapua.

” question everything “

ken

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John Alexander posted this 18 February 2015

Joe,

Sorry that my original question was not clear although you have it right.  In hindsight I should have only asked the first question. -- Does indexing imperfect bullets ever improve group size.

I made it too complicated.  My testing always failed to show that it helped and apparently your's didn't find any improvement either.  I was hoping that somebody had had positive results since so many folks are spending the time doing it.

"Now these imply that that accuracy increases happen when imperfect bullets with varying types and magnitude of imperfection are indexed, and I don't know why anyone would suspect that this would be the case."

I agree that if the imperfections are varying in types and magnitude and location it would be strange to think that indexing might help -- and this describes most defects we talk about.  Is there a type of defect that shows up in the same location relative to the parting line of the mold so indexing might help? 

Your suggested protocol for testing the indexing of both bullets and cases would work but It would be start if shooters would just test whether there is any actual bullet defect that can benefit from indexing.  As it stands now, as far as I know, there is no such evidence.

John

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joeb33050 posted this 18 February 2015

This is approximate for 5 shot groups.

If the hypothesis is: There’s a difference in group size when we do or don’t index.” , and we’re indexing both case and bullet, then we need to shoot some number of groups to test this hypothesis-some indexed and some not. One group each is a “pair” .. 

 

Now, how many groups must be fired to test the hypothesis? 

One of the ways to get a guess at the number of groups that should be fired is using the “paired difference” t test. I solved this for n for several levels of confidence:

 

The number of group pairs that must be fired depends on 2 things: how confident you want to be in your answer and the % difference in pair averages. 

If we want to be 90% confident that our answer is right, and the average difference between group sizes is 5 %, we need to shoot more than 30 pairs of groups, more than 60 groups.

 

90% confident, 10% difference, 13 group pairs

90% confident, 15% difference, 7 group pairs

90% confident, 20% difference, 4 group pairs

95% confident, 10% difference, 21 group pairs

95% confident, 15% difference, 10 group pairs

95% confident, 20% difference, 6 group pairs

97.5% confident, 10% difference, 29 group pairs

97.5% confident, 15% difference, 14 group pairs

97.5% confident, 20% difference, 9 group pairs

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John Alexander posted this 18 February 2015

In my opinion any serious shooter who really wants to find out if changing something really changes group size or if the two groups he is  staring at are just an accident and the next two will give the opposite answer, should copy Joe's little table and use it. When you think you see a difference between two powder charges, two primers, two seating depths, or between indexing or not indexing, etc. check the table and see how many groups you have to fire to be fairly sure it isn't just natural variation that makes the first two groups show a difference.    Everybody should be able to understand the table.  No complicated calculations. No computer needed. Using it would help us avoid thinking some goofy procedures somebody thinks up is real and would keep us out of a lot of  blind alleys, or up the wrong alley and wasting our time. Where we no spend a lot of our time.

This doesn't automatically mean that you always have to shoot lots of groups to be fairly sure that the difference is real. You only need lots of groups if the difference is small.  As the table shows, if the difference is 20% four pairs of 5-shot groups will give you pretty good assurance that you are on to something not just looking at the normal variation in group sizes.

For instance, the several hundred percent improvement Marshall claimed for indexing in Col. Harrison's “Cast Bullets” would probably require only one pair of groups to be pretty sure it was true.

John

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TRKakaCatWhisperer posted this 18 February 2015

John Alexander wrote: ... Is there a type of defect that shows up in the same location relative to the parting line of the mold so indexing might help? 

...

Yes!  Joe's going down the right path in sorting out whether or not there is a detectable difference among a given set of bullets when they are or are not indexed.  Good research.

Next question which you raise here is slightly different; additional tests can measure the effects of size and location of specific defects.  What size of defect (simulating a void) is detectable?  And then, as the size is varied, at what point does the effect become measurable on the target?

 

 

 

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adrians posted this 19 February 2015

This has been an interesting discussion, me knowing nothing about indexing but own a indexed mold. I can see the advantage of marking one cavity of a multiple cav mold to indicate your “best bullet cavity” but this one is a single cavity mold and I'm told its a tapered bullet so maybe this was indexed to be breach seated at 12.00 every time,,,, Am I way off here ,? I don't mean to hijack if so ,sorry.  

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joeb33050 posted this 19 February 2015

John Alexander and I have been proclaiming the heresy that “the name of the game is the same” is not true; that controlling variables to precise tolerances and performing uniforming operations does not markedly reduce group size. Weight-segregating primers and/or peening extractor grooves to .0005” tolerance ain’t going to do it.
I’ve been estimating the number of groups that must be fired to attain varied confidence level/% difference levels for over 25 years. None of my solutions is absolutely correct for arcane reasons, but they’re close and sum to: It takes a lot of groups to be very sure of a small difference in group size. 
 
John, and I with less enthusiasm, recommend experimentation, analysis, recording and reporting. It isn’t happening, and it’s not going to happen. The number of groups required, the religious fervor of the powder-weighers and the dogmatic belief of the “all guns are different” chanters discourages experimentation.
 
There is another approach. 
 
Imagine that there were some cast bullet shooters willing to do a little experimenting, and some others willing to sum and analyze the results, and yet some others willing to organize.
 
Imagine that we wished to know if indexing bullets reduced group size, that there were 20 shooters willing to shoot three groups indexed and three groups not indexed and report the results.
 
We would have 60 pairs of groups, indexed and not; enough to analyze and make some statement.
 

This would get us over the large-number-of-groups hump.    

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John Alexander posted this 19 February 2015

adrians: I think you are right about the purpose of the indexing mark.  It is hard to know but I believe a substantial percentage competition shooters index and some non-competitors as well. John

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OU812 posted this 19 February 2015

Bullets should also be indexed in sizer before sizing and seating gas check.

I always size nose first in my RCBS Lubramatic using hollow nose punch to square check at bullets base. Then finish pushing bullet thru sizer die using square face sizer stem to prevent nose distortion of bullet.

Lately I have been experimenting with pan lubing and hand dipping to prevent bullet distortion.

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joeb33050 posted this 19 February 2015

OU812 wrote: Bullets should also be indexed in sizer before sizing and seating gas check.

I always size nose first in my RCBS Lubramatic using hollow nose punch to square check at bullets base. Then finish pushing bullet thru sizer die using square face sizer stem to prevent nose distortion of bullet.

Lately I have been experimenting with pan lubing and hand dipping to prevent bullet distortion.Ya know, I scored a really big pail of wheelweights for only $3.61!!!Anyone know if you can shoot gas check bullets without the gas checks? Is it legal in CBA competition? 

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adrians posted this 20 February 2015

John Alexander wrote: adrians: I think you are right about the purpose of the indexing mark.  It is hard to know but I believe a substantial percentage competition shooters index and some non-competitors as well. John
Thanks John , I thought I was on the right track . I don't breach seat nor index , wouldn't know where to start but I think the subject is very interesting and you guy's have enlightened me about all these funny looking dimples on a couple of my molds. All I know is the one in the pic shoots pretty good out of a couple of  my 8mm's. Thanks guys.

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RicinYakima posted this 20 February 2015

Joe, You only need 19 others. I will shoot 6 five shot groups for you. Ric

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John Alexander posted this 20 February 2015

Be glad to shoot three pairs of 5-shot groups.  18 more volunteers needed.

This shouldn't require much work for shooters already indexing and are curious.

I will be glad to shoot more pairs is we are a little short of volunteers.

John

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RicinYakima posted this 21 February 2015

Me too, as I am getting ready to start practicing for the matches in June. Ric

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billglaze posted this 21 February 2015

I'd be glad to help out on this project. Just lay out the required parameters/conditions and I'll be good. I'll have to shoot some? Well, I'll just grit my teeth and carry on. Rotten job, but somebody has to do it. I'd really like to omit a lot of the items that I started under the “monkey see, monkey do” mental conditioning, but I keep coming back to them under the logic banner of “well, maybe it doesn't do any good, but it can't hurt." Sure like to have some hard proof that I could omit at least some of the procedures. Bill My eventual goal has to eventually come up with loads/procedures that will me allow me ti have sub-moa competitive groups while loading with my Dillon progressive presses. May be an unreachable goal, bit I'll keep striving.

In theory, there's no difference between theory and practice. In practice, there is. My fate is not entirely in Gods hands, if I have a weapon in mine.

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TRKakaCatWhisperer posted this 21 February 2015

Snow and ice here in VA.  When it melts ....

 

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John Alexander posted this 23 February 2015

Yesterday I discovered that I have a mold with .003” misalignment between the halves and .002” out of round.  That should be a good bullet for trying indexing.    I will see if it will shoot in my Ruger #1 so I can index well.

John

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cheatermk3 posted this 25 February 2015

John Alexander wrote:

"...After finding the thin side and marking it with a cut in the rim, have you ever shot a test of a series of alternate groups with the case indexed in one orientation (say 12 o'clock) versus identical loads with the index mark randomly positioned (around the clock so to speak) to measure the benefit indexing cases by the thin side? “

Sorry not to have responded sooner but I lost track of this thread... To answer your question , John, No, I have not.

I don't mark the thinnest portion of the case wall for any reason other than wanting a “standardized” reference point.  I could just as easily have used the thickest side; just wanted to be consistent. 

My reasoning is that I'm striving  to align the centerline of my loaded round as closely as possible with the centerline of the bore.  I was using an RCBS concentricity gauge to indicate the variation in wall thickness.

I do not at present own a tubing micrometer (I just a few minutes ago ordered one from midway) but when turning my necks just enough to remove the “high” spots and having the portion of the neck that is un-touched line up with the “witness mark” cut into the rim told me I had indeed found the thin side.

Since I turn the necks after marking the rim I have none to use for the testing being proposed here.

I'm about to start prepping a lot of cases for match shooting and I will leave 12 cases marked but not turned.

When I get to that point, I'll try shooting a few groups for the testing Joeb is proposing.

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