This morning I took a second look at the results Joe recently posted in his thread “SOME ACCRACY THOUGHTS” . He was reporting on three different load levels of one powder and was shooting a string of four 5-shots for each load. Joe often reports the size of each individual group in a string as well as the average of that string, an admirable practice IMHO.
I noticed how much the size of his groups varied within each string. I scribbled some numbers and found that the average percentage that the largest group in each four shot string exceeded the smallest group in the string was well over 100%, or the biggest groups were more than twice a big as the smallest groups in the same string.
If the wide variation between groups with the same load was noticed at all, a reader might assume a shaky old guy in Florida caused the variation in group sizes. My groups vary similarly – or course you might say OK, two shaky old guys. Or the reader might assume that the old guys cast very poor quality, are too lazy to weigh sort them, and bullet quality is responsible for the wide variation from group to group as well as the fliers in the groups. (In fact, that is the kind of assumption many of us erroneously make when we notice more variation than we like in where our bullets hit.)
However, if you haven’t noticed similar variations in your own groups, take another look or take a look in the test results in “Dope Bag” section of the American Rifleman. The AR standard testing standard is five 5-shot groups and they report both the smallest and largest group in each string. If you average 8 or 10 of these results you will find that the average that the biggest groups exceed the smallest in the same string will be pretty close to 90%. It seems unlikely that the AR editors are all old and shaky or are shooting defective bullets. This variation occurs in the testing of pistols and inaccurate rifles as well as in the testing of ugly “tactical” rifles that sometimes shoot much better.
I think this little factoid is more that just idly interesting. It might be productive to think about this surprising and unavoidable variation in group sizes in relation to the common practice of finding optimum loads by shooting a one 5-shot, or even one 10-shot, group for each load being tested. Yes, 10-shot groups vary less but still a lot.
And because this variation seems to be independent of the quality of either the rifle or ammunition it is also worth thinking about in relation to fliers.
John
Think About It
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- Last Post 05 January 2016
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John, Joe Gifford, Russ Harman and I were working on some Ransom Rest test with Ed Harris on his 38/200 articles. The picture below is the common backer for 102 record shots from the same revolver. Just above the center right you see an area totally shot away. This is from 4 of the loads used. The other holes are from 6 loads that did not group well. (Please note several profiles of bullets tumbling.) However, they are almost all low and left. They are not flyers, but part of the normal group dispersion for those loads. They are just the outliers of that load's group. All loads that shot small groups, shot them to the same point of aim. And by the machine, not by hand. My point is that a flyer should be outside of the normal group, not just one on the edge of normal. And you don't have enough data points with 5 five-shot groups to tell you anything. Actually I an surprised that only 100% larger groups are made with that number of groups. .jpg?width=690&upscale=false” alt=)
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Assume that shot x and y are distributed normal and we can model distributions of group sizes. We find that with sets of five, 5 shot groups, on average, the largest is 1.91 times the smallest. Recording group size data in EXCEL, the spreadsheet includes LARGEST/SMALLEST for sets of 5 groups-sometimes there are less than 5 groups shot-lack of bullets or??? Anyhow, for the Savage FV in 223, there were 83 sets of five, 5 shot groups fired. The average LARGEST/SMALLEST = 2.103, close to 1.91. This real world DATA suggests to me that the assumption of normality and the 1.91 estimate are supported pretty well.
Modeling group size and monte carlo repeats allow us to tell about anything about groups. We can answer about any question about group sizes.
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Something that I would like to bring up, regarding this subject, is “conditions".
If it's groups shot indoors at 50 ft, I can see discounting them but, at 100 yards and especially 200 yards, I believe they play at least a moderate if not a big role in ES's of groups.
In my sport, the reading of conditions is extremely important and that would hold true for Mil, Hunter and Production classes, too as most of them are shot at simular velocity 13 - 1600 fps) Heavy and UN classes are less effected but, still a factor.
I think most will agree that the shooters that win the most (therefore shoot smaller groups) are those that can gauge conditions the best.
I truly wish that I was a lot better at doping conditions than I am and I almost always ascribe my fliers to NOT calling a condition.
Frank
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Ric, It is obvious that if we are to get anywhere in discussing “fliers” we have to agree on the definition. Joe usually uses the term “outliers” to mean shots that are probably out there for some physical reason (individual defects of all kinds, gusts of wind, mirage,etc.) This as opposed to shots that are out there just because random variation put them there. Joe suggests that for five shot groups that is usually a shot that increases the group size by 70% if I understand him correctly. In a recent post he seemed to use the term flier as the same thing as outlier. Your post also seems to use flier the same way. That would be fine if we could all agree on that definition.
However, from observation I don't believe that most shooters use the term flier only that way. Holes that increase the size of the best four shots by much less than 70%. are called fliers all the time. I have heard shooters say that their rifle and load will shoot 1” groups if fliers didn't increase them to 1.4". That use of flier may not be “correct” if there is a correct definition, but that's the way it is used by most shooters.
I generally use the term as I hear people using it because I am trying to communicating with shooters not statisticians. I think these two different definitions are causing us to seem to disagree when we really don't.
John
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Something that I would like to bring up, regarding this subject, is “conditions".
If it's groups shot indoors at 50 ft, I can see discounting them but, at 100 yards and especially 200 yards, I believe they play at least a moderate if not a big role in ES's of groups.
In my sport, the reading of conditions is extremely important and that would hold true for Mil, Hunter and Production classes, too as most of them are shot at simular velocity 13 - 1600 fps) Heavy and UN classes are less effected but, still a factor.
I think most will agree that the shooters that win the most (therefore shoot smaller groups) are those that can gauge conditions the best.
I truly wish that I was a lot better at doping conditions than I am and I almost always ascribe my fliers to NOT calling a condition.
FrankHere “Wind” is what Frank calls “conditions". Absent data at least suggesting otherwise: Wind affects accuracy least, although much more as range increases. Skill affects accuracy more, but less than Equipment. It's hard to imagine an Equipment improvement, above the Heavy class equipment, that is as great as the difference between Production and Heavy equipment. These changes in group size don't simply add. The changes, in inches, must be squared, the squares summed, and the square root of the sum is the combined change. If the effects of Wind, .046", and Equipment, .345” were eliminated, and Skill improved from Second to First,
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"Wind” is what Frank calls “conditions". No, mirage is also included in “conditions".
"Wind affects accuracy least” Add mirage here.
I just can't get behind that statement and I don't think that competitive shooters, will either.
"Skill affects accuracy more", yes and when combined with “conditions” WILL, lead to smaller “fliers".
When you do you stats, you are also adding (w/o realizing it) the shooters ability at both holding and ability to gauge conditions.
I think the stats would be better served by using the first place finishers in match results.
Frank
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In the 5 five shot group testing are we ascribing any shot outside the “average” of the 5 groups as a “flyer"? or any shot outside the smallest group shot with a particular load?
I'm beginning to question if what we call are calling “flyers” (or “outliners") here aren't really flyers in the usual external ballistics sense of the word.
LMG
Concealment is not cover.........
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Let me take a run at this. If I fail to connect the dots, I apologize in advance. My hypothesis is that we are all looking for a valid way to isolate and quantify the variance in our results caused by less than perfect bullets. If i shoot a 5 shot group and 1 shot is not where I want it to be, I think we could all agree that it is not proof that the bullet was flawed. If I shoot 4 groups? 10 groups? 20 groups does it become easier? How about if our Heavy rifle national champion was doing the shooting? Do the basic answers we are seeking become easier to identify. His average group size will be smaller. The variance in his group size measured in MOA will get smaller. There is , however, no proof that his variance in group size measured relative to his equipment and his abilities would get any smaller. Simply put his variance as a percent of his group agg wouldn't necessarily vary one bit from that of a less accomplished shooter.
Now if our expert were to fire 100 groups with the most perfect bullets we can make, we will get a distribution of measurements that may well be a normal distribution as Joe suggested. If it is we now have a distribution of groups with a mean and with a standard deviation we can calculate. (1000 groups would be better). No shot was an outlier as we were using our most perfect bullets. The next day is an identical day. Conditions are the same, the shooter is the same, the equipment is the same, etc. We now substitute bullets that all have rounded edges on their bases. Our shooter fires his first group and there is one shot uncomfortably away from the rest. An outlier - not necessarily. We need to have all 100 groups. Now we can calculate a new mean and standard deviation .
Now we can see what impact our rounded edges had. No single shot or no single group helps us. The logistics of this approach are a problem of course. I suppose the most practical solution would be a single shooter alternating groups - lets say 40-5 shot groups. 20 with perfect bullets and 20 with similarly flawed bullets. These groups would need to be alternated and the actual order would need to be “blind” to the shooter to avoid bias. No single shot or no single group still will help us. It is only when we compare the two statistically valid sets of groups that we may be able to draw a conclusion.
Until then you may be assured that any shot I fire which does not hit where I want will be labelled a flier.
I am sorry this got too long.
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For the purpose of our discussion I propose that we define “flier” as any shot in a five shot group that increases the size of the group from 20 to 70% over the group size of the four closest shots. The great majority of these are caused by the natural variation as explained by Joe above and are seldom the result of defective bullets. My testing hints that this is true but to prove it solidly enough to convince more shooters we need more testing.
Shots that increase the size of the group of the four best shots over 70% in good shooting conditions (whatever that means) and all the holes that are clearly caused by bullet or load defects like the one pointed out by Ric in his 102 shot group should be called “outliers.” Outliers could be cautiously considered as possibilities for deleting from test data. Fliers should never be deleted from the test data.
My reason for suggesting the 20-70% be the criteria for the term flier is because I think that fairly well matches what a lot of shooters now call fliers. I think that unless we adopt some similar definitions we will have a hard time communicating.
John
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"Wind” is what Frank calls “conditions". No, mirage is also included in “conditions".
No Frank, “Wind", my definition, is what you call “conditions", your definition.
"Wind affects accuracy least” Add mirage here.
I just can't get behind that statement and I don't think that competitive shooters, will either.
It doesn't matter if you or anyone else can “get behind” that statement, until you or someone comes up with some DATA to refute it, it's there, out in front of you. Show us the data Frank, show us how shooters compensate for “Wind” = “conditions", and how much. Otherwise you're expressing opinions about facts, Frank, and that doesn't make sense.
"Skill affects accuracy more", yes and when combined with “conditions” WILL, lead to smaller “fliers".
When you do you stats, you are also adding (w/o realizing it) the shooters ability at both holding and ability to gauge conditions.
You have no idea how I did this analysis, Frank, you never read it. I think the stats would be better served by using the first place finishers in match results.
Show us how to do that, Frank. Please. Frank
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For the purpose of our discussion I propose that we define “flier” as any shot in a five shot group that increases the size of the group from 20 to 70% over the group size of the four closest shots. The great majority of these are caused by the natural variation as explained by Joe above and are seldom the result of defective bullets. My testing hints that this is true but to prove it solidly enough to convince more shooters we need more testing.
Shots that increase the size of the group of the four best shots over 70% in good shooting conditions (whatever that means) and all the holes that are clearly caused by bullet or load defects like the one pointed out by Ric in his 102 shot group should be called “outliers.” Outliers could be cautiously considered as possibilities for deleting from test data. Fliers should never be deleted from the test data.
My reason for suggesting the 20-70% be the criteria for the term flier is because I think that fairly well matches what a lot of shooters now call fliers. I think that unless we adopt some similar definitions we will have a hard time communicating.
John Shoot a gun that averages 1” 5 shot groups and some groups will be >1", some <1".
The more groups shot, the larger will be the largest and the smaller will be the smallest.
Shoot enough groups and start to see some few VERY big groups, with one shot WAY out.
BUT, the gun still averages 1” 5 shot groups.
Every group will have 1 shot that makes the group > the other-four-shot-group size.
WAY out shots are either the result of natural variation, or some STRANGE thing happening.
We can NEVER tell what caused one shot to be WAY out. We CAN say this: If 1 shot makes a 5 shot group ~ 1.7or more X as big as the other 4 shot group, we would expect this to happen only ~4.5% of the time by natural variation. Thus, ~95.5% of the time this shot location is caused by a STRANGE thing.
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Shoot a gun that averages 1” 5 shot groups and some groups will be >1", some <1".
The more groups shot, the larger will be the largest and the smaller will be the smallest.
Shoot enough groups and start to see some few VERY big groups, with one shot WAY out.
BUT, the gun still averages 1” 5 shot groups.
Every group will have 1 shot that makes the group > the other-four-shot-group size.
WAY out shots are either the result of natural variation, or some STRANGE thing happening.
We can NEVER tell what caused one shot to be WAY out. We CAN say this: If 1 shot makes a 5 shot group ~ 1.7or more X as big as the other 4 shot group, we would expect this to happen only ~4.5% of the time by natural variation. Thus, ~95.5% of the time this shot location is caused by a STRANGE thing. Joe, I am in complete agreement. Does that somehow conflict with my claim that we need definitions? John
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"We can NEVER tell what caused one shot to be WAY out. We CAN say this: If 1 shot makes a 5 shot group ~ 1.7or more X as big as the other 4 shot group, we would expect this to happen only ~4.5% of the time by natural variation. Thus, ~95.5% of the time this shot location is caused by a STRANGE thing.”
Joe, Why didn't you say it that way before? Now my little mind can get around that concept.
Ric
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I started this thread to discuss that the size of groups with the same load, rifle and shooter vary way more than most shooters think they do. Ric says he is surprised that they don’t vary more but most shooters apparently think nothing of the kind since they routinely report that they use one 5-shot group at each load level in finding best load and one pair of 5-shot groups to see which lube, seating depth, primer, etc. is best. They would have better luck if they used bigger samples. Because so many shooters are spinning their wheels and don’t know it I think this deserves discussion and an article in TFS to try to help them.
However, I also mentioned fliers. Fliers immediately took over the thread. I suppose that is some kind of measure of the interest in fliers. Talking about fliers is OK by me, I will start another thread about the variation of groups. Let’s keep on discussing fliers since we have had a lot of good posts. All shooters should read Joe’s explanation in post #12 over until they understand it.
Things I think people in the discussion understand include: We can’t ever be sure that the individual shot that enlarges the best four shot group has a physical cause or is just natural variation (see post #12). However, if the shot enlarges the four shot group a small amount it is more likely to be caused by natural variation than a shot that enlarges the four shot group more. Thus when the percentage increase is very small the chance that is just natural variation approaches 100%. Joe tells us that at 70% increase there is only 4.5 percent chance that it is natural variation. This is true for small groups (high quality equipment, shooter, and conditions) and large groups (not such high quality inputs.)
If I am wrong about my assumption of agreement in the paragraph above we perhaps need to discuss disagreement first.
John
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I'll butt out of this discussion but, first I'd like to address these two questions, since they are directed at me:
You have no idea how I did this analysis, Frank, you never read it.
Please tell me/us how that you resolved the “fliers” when shot in 5, 10, 15 and 20 mph variable winds and what direction the wind was, as well as how often the conditions occurred? You CAN NOT say that it doesn't matter as a 10 mph with at 90 deg the bullets direction will cause a .28 BC (a average 30 cal BC. 22 cal BC's are usually way lower) bullet shot at 1600 fps, to be dispersed by 2.91". Saying that it's accurate because it from a large sample, doesn't cut it, as you are just measure how that the majority of shooters can't read conditions, accurately and I believe that, that's what is being measured, is their inability to gage conditions. If your data was shot in a vacuum or a indoor range I will concede.
"I think the stats would be better served by using the first place finishers in match results." Show us how to do that, Frank. Please.
I would suggest that you take shooters scores that are record holders, and follow their results at all matches that they shoot and the first place finishers results from the last 5 years at the yearly National shoot and use that info for the flier stats. It won't be as accurate as groups shot indoors but, as they will be much better at calling all “conditions", it will be much more accurate than any other single or other groups of shooters and I would have much more confidence than saying that conditions mean little, it just a plain fact, that reading conditions is the reason that most, if not all matches are won.
In addition, if you will take my results, seriously, next time out, I will shoot 4 five shot groups, watching the conditions with my flags and in alternating targets, shoot the same number of groups in unfavorable conditions.
I'm NOT posting to be negitive, I'm posting for accuracy. I'm a competitive shooter and have to deal with these things at each match, that I shoot. For me, the most important thing in accuracy IS reading conditions and the better I do at reading the conditions, the better I place. What some people call “fliers” I call a missed condition!
Frank
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I bought 3# of Titegroup, got the 22-250 Striker shooting with it, easy and fast- then tried to get the Savage 12 FV going yesterday. Last time with the FV; 5, 5.5 and 6 grains produced big ugly groups, too big to measure. Loaded 3.5, 3.9, 4.3 and 4.7 grains and shot them yesterday. 3.5 grains, 3 groups of 2.85", 2.95” and 3.15” 3.9 grains, 1st group missing a shot, it just isn't on the paper. Then 4.0” and 1.7” 4.3 grains, 1st group is an even 8", see the picture 4.7 grains, no measurable groups I went home, unscrewed the varmint weight barrel off the gun and screwed on a 22” light sporter barrel. There's got to be something wrong for the gun to shoot so erratically. This brings up a caveat. In talking about groups and fliers and anything measured and statisticed, the process must be operating smoothly. Groups can be big, but they've got to be sorta round and sorta consistent. Not like mine. My results are telling me that something is amiss, something is causing wild changes in where them bullets hit. I've got to find and fix that before doing much more analysis.
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Joe, Have you checked your telescope and your mounts.Mike.
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Joe, Have you checked your telescope and your mounts.Mike.
Mike;
Yes, and checked everything else I can think of.
Yesterday, after the very poor shooting, I shot 5 shots of a known fair load into ~1.5". The rifle will shoot some loads fairly reliably < 2", but other loads, Titegroup so far, just wild.
Today I'll take everything apart and see if I can find the gremlin.
Thanks;
joe b.
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LARGEST OVER SMALLEST GROUPS IN SETS OF GROUPS
5 SHOT 10 SHOT
GROUPS LARGEST/ LARGEST/
SHOT SMALLEST SMALLEST
2 1.36 1.25
3 1.59 1.39
4 1.77 1.50
5 1.91 1.59
6 2.03 1.66
7 2.14 1.71
8 2.24 1.77
9 2.33 1.81
10 2.41 1.86
Here's the table. For 5 shot groups, when 7 groups are shot, the largest/smallest is 2.03. Means that if we were to shoot MANY sets of 7 five shot groups and measure the largest/smallest, the AVERAGE largest/smallest would be 2.03. OR, if we shoot 7 five shot groups and measure them, we would EXPECT the largest/smallest to = 2.03.
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Let me take a run at this. If I fail to connect the dots, I apologize in advance. My hypothesis is that we are all looking for a valid way to isolate and quantify the variance in our results caused by less than perfect bullets.
John contends and I agree that minor flaws in bullets do not markedly/measurably affect accuracy. There are two questions. 1. What means “minor". 2. Can we prove/disprove John's contention?
If i shoot a 5 shot group and 1 shot is not where I want it to be, I think we could all agree that it is not proof that the bullet was flawed. If I shoot 4 groups? 10 groups? 20 groups does it become easier?
I often shoot a 5 shot group and 1 shot is not where I want it to be. I do it all the time. I don't suspect that the bullet is flawed, certainly not at first. Don't we have to shoot flawed bullets and THEN measure groups?
How about if our Heavy rifle national champion was doing the shooting? Do the basic answers we are seeking become easier to identify. His average group size will be smaller. The variance in his group size measured in MOA will get smaller. There is , however, no proof that his variance in group size measured relative to his equipment and his abilities would get any smaller. Simply put his variance as a percent of his group agg wouldn't necessarily vary one bit from that of a less accomplished shooter.
This seems to be correct, repeated arithmetic extravaganzas tell us that for 5 shot groups the STDEV = .269 X average group size, and for 10 shot groups, .1947 X average group size. I think STDEV is what you mean by “variance", but if you mean VARIANCE, still true of course. I was surprised at this, it took me a long time to accept it.
Now if our expert were to fire 100 groups with the most perfect bullets we can make, we will get a distribution of measurements that may well be a normal distribution as Joe suggested. If it is we now have a distribution of groups with a mean and with a standard deviation we can calculate. (1000 groups would be better). No shot was an outlier as we were using our most perfect bullets. The next day is an identical day. Conditions are the same, the shooter is the same, the equipment is the same, etc. We now substitute bullets that all have rounded edges on their bases. Our shooter fires his first group and there is one shot uncomfortably away from the rest. An outlier - not necessarily. We need to have all 100 groups. Now we can calculate a new mean and standard deviation .
This would tell us if rounded edge bullets shoot bigger groups with bigger STDEVs than perfect bullets. I have posted results of my experiments looking at this. However, this might not be the question. Here's my take on the question: If some bullets with minor flaws are mixed with perfect bullets, and if minor flawed bullets make bigger groups than perfect bullets, then what is the distribution of 5 shot group size as the percentage of minor flawed bullets varies? If all the bullets have minor flaws, all groups are bigger. If one minor flawed bullet is mixed with 99 perfect, then only 1 5 shot group will have a minor flawed bullet, AND that bullet could shoot in the group with the other four. Because, almost half the minor flawed bullets will be in the 4 shot group.
Now we can see what impact our rounded edges had. No single shot or no single group helps us. The logistics of this approach are a problem of course. I suppose the most practical solution would be a single shooter alternating groups - lets say 40-5 shot groups. 20 with perfect bullets and 20 with similarly flawed bullets. These groups would need to be alternated and the actual order would need to be “blind” to the shooter to avoid bias. No single shot or no single group still will help us. It is only when we compare the two statistically valid sets of groups that we may be able to draw a conclusion.
Until then you may be assured that any shot I fire which does not hit where I want will be labelled a flier.
I am sorry this got too long.It took me a long time to think about this. An interesting post.
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just a thought .... but i don't recall when using mj bullets that ::
changing any one of 15 suitable range gunpowders ..... enlarged groups from 2 inches to 7 inches .
maybe from 0.7 moa to 1.4 moa ... but never wild ...miss-the-paper wild ....
maybe joeb will catch the villain in the act !!
ken
why are cast bullets so easily offended ??
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I may have mentioned this at one time in the past. Back when I was doing my Food Science MS (no graduate group for wine then) we used Analysis of Variance ANOVA. Back then we used a Main Frame VAX computer to do it but I believe that today, Excel can do it. We were looking for differences in wines, using a panel of trained judges, over a number of days. We could say (Lies, dammed lies and statistics) that with 99% confidence that there was a difference and where it came from (judge, day or wine).
I would be that we could do the same for bullet, shooter and conditions (days at the range). I will do some digging and see what I can come up with.
Dave
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Good link:
73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia
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I am stuck in a motel while trying to fly home from OR so am late with this comment. But if the question is does a certain size defect cause the average accuracy to increase? Or is it insignificant? < If we can forget the difficulty of quantifying wrinkles or rounding for a minute -- think weight variation for the first type of defect.> I believe JSH nailed it with this paragraph.
"I suppose the most practical solution would be a single shooter alternating groups - lets say 40-5 shot groups. 20 with perfect bullets and 20 with similarly flawed bullets. These groups would need to be alternated and the actual order would need to be “blind” to the shooter to avoid bias. No single shot or no single group still will help us. It is only when we compare the two statistically valid sets of groups that we may be able to draw a conclusion."
Amen! I have done quite a bit of this kind of testing without finding accuracy degradation for either weight variation or some very visible casting defects. I wish someone would try to prove me wrong instead of going off on all kinds of tangents.
John
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I just reread my last night's post and I sounds a bit cranker that I intended. I have nothing against tangents -- shoot off on quite a few my self. The tone may have something to do with this trip.
I will refrain writing a serious post tonight and avoid sounding grouchy since I am spending another night in another motel on what was supposed to be a one day trip from Oregon to Maine. The wonders of modern air travel. Tomorrow will be day three and since there is between 10 and 15 inches of new snow in the area to drive through tomorrow. I could go for a 4 day trip if this string of less than perfect luck holds out.
John
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John, Any modern trip involving air planes is a good trip if you are alive and your luggage arrives within 2 weeks. Best of luck on your journey! Ric
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You are right Ric that puts things in perspective. I have only had to get out of flying machine that was upside down at the time and I was well enough to walk to a road. I should be thanking my luck instead of grumbling.
John
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OMG ( golly ) ....no ! don't fly !! i used to fly a lot ... but last time from cal. to st. louis i was in the plane ready to taxi when the plane was stopped ... a home security ” worker bee ” had missed a customer and so all the planes were emptied and about 2000 people missed their flights ... had army reserves with sub machine guns ordering us from one side to the other of the terminal ... oops missed someone again ... now upstairs them screen downstairs ... now it's midnight ... travelers were freaking out and assaulting home security workers ...
oh well i got home a day late ... no future courtesy tickets .. not even free peanuts ...
oh, i haven't flown since . i am afraid i might decapitate the guy ahead of me putting his seat back into my crotch ...
no place like home; don't fly .
ken at home .
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I am so happy that my youngest and his wife moved back to Calif. from DC. I don't have to go through those horrible crowded (can't afford 1st class)seat LOOOONG flights every year to see them and the Grand Kids. It's bad enough to have to drive to Ca. Brodie
B.E.Brickey
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Ken, The last time I flew was my Mother's funeral, Dayton OH to Seattle was 28 hours in the middle of summer. I told my brother when he crocks, I'm driving so plan the funeral at least a week later. They fill the body full of chemicals, so what does it matter? Ric
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Well, I'm off to Florida to see the girl and her husband for the month of February. Daytona 500 and Bike Week. Can't wait to get out of winter, I hate it more every year. You can all bet I ain't driving THAT FAR. Gp
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I started this thread to discuss that the size of groups with the same load, rifle and shooter vary way more than most shooters think they do.
Agree.
If you use Taran to analyze your groups -- and I know I probably the only one here who does :D -- it will tell you that anything less than 40 shots is insignificant, at least with regards to small improvements between loads.
My philosophy is this: if a load shoots really really really bad, you don't need a lot of shots to prove that it is bad. If it shoots a pattern instead of a group, you know it's a bad load.
But if you are trying to prove that one load is 10% better than another load, that's tough, and will take a lot of shooting to prove a statistically significant difference.
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Re: fliers. My personal policy is to count every shot including “fliers” unless there is one heck of a good reason not to -- like if you discover that your scope has rattled loose. In which case, since I'm not sure when the scope rattled loose, I would scratch the whole group and start over.
Using mean radius instead of group size will diminish the importance of fliers.
Using mean radius instead of group size will diminish the importance of whether you shoot 5-shot groups or 10-shot groups. In theory, a given load will have the same mean radius whether you shoot 3-shot groups, 5-shot groups, or 10-shot groups.
Joe has pointed out that you can predict mean radius from group size. But that is only true if you have enough groups.
The bottom line -- it takes a whole lot of shooting to prove that one load is 10% better than another load.
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I have done quite a bit of this kind of testing without finding accuracy degradation for either weight variation or some very visible casting defects.
Physics says that an unbalanced bullet will cause dispersion in proportion to RPM. Try repeating your tests at 200,000 rpm ? :cool:
Harold Vaughn quantified this nicely in his book “Rifle Accuracy Facts." He actually built a device to measure the imbalance in bullets (not sure if his device would work with our cast bullets?). Even match grade jacketed bullets are imperfectly balanced, never mind our humble cast bullets.
HOWEVER Vaughn also pointed out that total dispersion is the square root of the sum of the squares of all the individual dispersions. What this means in practical terms is that if you totally eliminate one source of dispersion, like imbalance, overall dispersion may not improve much because all those other sources of dispersion are still there. And if the improvement is only 10%, lotsa luck proving it ! :D
We need to figure out what our BIG sources of dispersion are and go after them first. That is what I hoped to determine with my water tank experiments.
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Mtngun,
I shot about 920/940 shots sorting reloading dies for the 30/06 in 2006. Therefore, I have no faith in 5 five shot groups. Since matches are won on 0.010” groups, or less variance, you better have good data before I have any faith in anyone's results.
Ric
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Mtngun,
I shoot about 920/940 shots sorting reloading dies for the 30/06. Therefor, I have no faith in 5 five shot groups. Since matches are won on 0.010” groups, or less variance, you better have good data before I have any faith in your results.If matches are won by 0.010” that means matches are won by luck, though no doubt a lot of skill is required to shoot that consistently especially in wind and mirage.
If you use Taran you can overlay your individual groups into one big group, Then it doesn't matter whether you shoot 2-shot groups or 10-shot groups, only that you fire enough shots. Example below of two 11 shot groups overlaid into one 22 shot group. Of course you don't need any fancy analysis to tell you that this is not a bragging size group. :D
Note Taran's “confidence meter” in the lower right corner. It takes a lot of shots to make Taran feel confident. :D
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My philosophy is this: if a load shoots really really really bad, you don't need a lot of shots to prove that it is bad. If it shoots a pattern instead of a group, you know it's a bad load.
But if you are trying to prove that one load is 10% better than another load, that's tough, and will take a lot of shooting to prove a statistically significant difference.
AMEN:
This has been explained several times in TFS in the last couple of years. And this past year in TFS #235 Joe presented a simple, easy to use, mathematical way to estimate how many groups are required to reach a reasonable conclusion that one load is better than another when the difference is 10%, 20%, etc. It is hard to believe that when one of two 10-shot groups comparing two loads is 20% better you only have the roughest guess and you need several more pairs to be reasonable sure that one load really is better. But that's the way it is.
Writers presenting accuracy results from one five or one ten shot group are giving the reader at best a rough estimate and possibly misleading information.
John
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Mtggun,
Looking at the last four years of National Matches, Military Rifle, Issue class, group scores I will stick with my “matches are won with 0.020” better groups. Mike Kastning won three years in a row because he was “lucky” for three years in a row? I don't think so, I think he beat the socks off the rest of us because he could shoot those 0.020” smaller groups more often than the rest of us.
Ric
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John, Joe does an exceptional job of sharing and analyzing his shooting data, though I took issue with certain points his article made. Joe says you don't need mean radius because you can predict mean radius from group size, I counter that you can predict group size from mean radius, and with fewer shots, too. :D
But we all agree that rarely can something be “proved” wtih 5 shots, or 10 shots, or often not even with 25 shots, other to prove that a certain load is not going to shoot well.
Another pet peeve of mine is that people often claim to “prove” something without using a control. I.e., “I use a magic bullet design and I've proven it works, see here's this solitary group.” And I always wonder, “BUT COMPARED TO WHAT?” It's always more convincing if we include an “ole reliable” control load in our experiments, preferably loaded at the same time and shot on the same day. Yeah, that takes a lot of shooting and we don't always have time, even if we are willing.
In practice I often compare “this week's load” to “last week's load.” It's better than no comparison at all, but sometimes leaves me wondering “maybe the range conditions were better last week? Or maybe I was just having a bad day? Etc..” :D :D :D
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Ric, the reason I question the 0.010” or 0.020” claim is that mathematically speaking, lotsa luck proving that one load or one shooter is 0.010” more accurate than another. Can you even dope wind and mirage to 0.010"? I can't.
The top competitive shooters that I have been acquainted with were very consistent. They didn't shoot a perfect score every time, but they shot a good score every time, and they shot regularly. I on the other hand, have gone for years without firing a shot. It's sad how making a living and taking care of family sometimes interfere with the important things in life. :D :D :D
Tony Boyer said something in his book that impressed me -- that he actually prefers to practice on windy days when the rest of us stay home. He reasons that anyone can plunk down the money to buy a gun that is just as accurate as his gun, and shoot groups just as good as his under ideal conditions, but he believes he holds an edge in poor conditions. That is probably true for most competitive precision shooting?
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If matches are won by 0.010” that means matches are won by luck, though no doubt a lot of skill is required to shoot that consistently especially in wind and mirage.
Some matches may be won by a smidgin, but on average:
AVERAGE GROUP SIZE RATIOS CBA NATIONAL MATCH data for 2000 to 2013, HVY, PBB, PRO and UNR shows the following ratios of averages for 5 shot 100 yard groups: Shooter 2 / Shooter 1 1.20 Shooter 3 / Shooter 1 1.33 Shooter 4 / Shooter 1 1.47 Shooter 5 / Shooter 1 1.55 So Shooter 2 average group size is 1.2 times the size of Shooter 1 group size. I hadn't done the analysis on 10 shot 100 yard groups until this morning, 11/29/13, and was surprised to find their ratios to be: Shooter 2 / Shooter 1 1.21 Shooter 3 / Shooter 1 1.36 Shooter 4 / Shooter 1 1.50 Shooter 5 / Shooter 1 1.55 It appears that there's some underlying relationship causing these ratios to be almost identical. I wonder why. See “CBA NATIONAL MATCH 10 SHOT GROUP 12345.xls"
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OK, I give up! My memories of all the matches I lost by 0.020” are insignificant to the total matches I shot (I went back and counted.). So how competitive are the Issue class military rifles? (For some reason this board will not let me post .xlsx “excel 2007” tables) The chart below has the first column the year, the second is the 100 and 200 yard five shot group aggregates of the winner, the third the second place shooter and the last the MOA difference between first and second. The winner's MOA was 1.8787 and the difference to second place was 0.1629 larger. So the second place shooter's groups are only 1.0867 times larger than the winners, much less than regular benchrest results.
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Physics says that an unbalanced bullet will cause dispersion in proportion to RPM.
We need to figure out what our BIG sources of dispersion are and go after them first. That is what I hoped to determine with my water tank experiments. Physics never said that to me. Harold did a lot of “dry-labbing", he should have taken that 270 to the range more often. Damaged bullets are unbalanced bullets, and we'd suspect that the more unbalanced, the greater the dispersion. If we damage a batch of bullets, all the same, we'd suspect that when shot, the dispersion increase would be about the same. If undamaged bullets shoot 1” groups, the damaged bullets should shoot outside or at the edge of a 1” circle. Damaged bullets should shoot doughnut-shaped groups. They don't. If anything, damaged bullets shoot what look like RANDOM NORMALLY distributed sets of shots, they look like BIGGER groups, they don't look like dougnut-shaped groups. So, if equally-damaged bullets don't shoot doughnut-shaped groups, then dispersion ain't constant, and dispersion ain't in proportion to unbalance. What this means is that we don't know what happens when we shoot a damaged bullet. Harold didn't know either. We can do physics and arithmetic at home all we want, but if the bullets don't follow the arithmetic, the arithmetic is wrong. Prove it to yourself. Get a 22 RF rifle, a box of 50 ctgs, and a file. File relatively-big wedges, about the same size, about the same place, out of each bullet. Shoot them all, all 50, at a big target-aiming at the same point. Some bullets hit close to center, some hit way outside, it just looks like a big group. Then, while examining the target, ask yourself this question: If damaged bullets are unbalanced bullets, why did some of these bullets hit so close to center? The policeman's lament, no doughnuts.
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OK, I give up! My memories of all the matches I lost by 0.020” are insignificant to the total matches I shot (I went back and counted.). So how competitive are the Issue class military rifles?
(For some reason this board will not let me post .xlsx “excel 2007” tables)
The chart below has the first column the year, the second is the 100 and 200 yard five shot group aggregates of the winner, the third the second place shooter and the last the MOA difference between first and second. The winner's MOA was 1.8787 and the difference to second place was 0.1629 larger. So the second place shooter's groups are only 1.0867 times larger than the winners, much less than regular benchrest results.
Ric; if you've got this info in EXCEL, please try this. I think your data got clumped.
For each year, for 100 then 200 yards, list the group sizes, first through 5th.
Calculate 2nd/1st, 3rd/1st, 4th/1st, 5th/1st for 100 and 200 yards
Do it for each year.
Average, for 100 yards, for all years:
2nd/1st
3rd/1st
4th/1st
5th/1st
Then average for 200 yards.
I'll bet a quarter that the results look like the numbers I got, above-at least for 100 yards.
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Joe,
I'll work on some of that today, as it is still snowing like crazy here. 193.4 inches last month on the pass behind my house, a new record for a December, not a high snow month.
But I will only do it for 1st place and 2nd place, as who cares below that? I'm only interested in winners, not the losers down the list. What does it take to WIN? The rest of us down the line are just there to be social and make noise.
Ric:fire
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Joe,
I'll work on some of that today, as it is still snowing like crazy here. 193.4 inches last month on the pass behind my house, a new record for a December, not a high snow month.
But I will only do it for 1st place and 2nd place, as who cares below that? I'm only interested in winners, not the losers down the list. What does it take to WIN? The rest of us down the line are just there to be social and make noise.
Ric:fireI'm interested in the ratios that are remarkably similar, 10 shot to 5 shot. If you send me the workbook, I'll work on it. If you can save it as an .xls workbook. I'm staying in today, it's 47 this morning, parka and mittens and wooly hats required. joe b.
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If undamaged bullets shoot 1” groups, the damaged bullets should shoot outside or at the edge of a 1” circle. Damaged bullets should shoot doughnut-shaped groups. They don't. If anything, damaged bullets shoot what look like RANDOM NORMALLY distributed sets of shots, they look like BIGGER groups, they don't look like dougnut-shaped groups.
So, if equally-damaged bullets don't shoot doughnut-shaped groups, then dispersion ain't constant, and dispersion ain't in proportion to unbalance.
What this means is that we don't know what happens when we shoot a damaged bullet. Harold didn't know either. We can do physics and arithmetic at home all we want, but if the bullets don't follow the arithmetic, the arithmetic is wrong.
-The policeman's lament, no doughnuts.
Joe,
When you argue against physics (assuming the assumptions and calculations used are both correct) you have usually saddled the wrong horse.
Doughnuts can be shot with unbalanced bullets IF the rifle is accurate enough and the unbalancing (defect) is big enough -- if you rotate the position (1 to 12 o'clock) of the defects as it leaves the muzzle. Larry Landercasper (the guy with the 25 shot group I used in TFS #229) has done just that with his rimfire rifle. I believe it was posted on this forum back when he posted the 25 shot group but I am not sure. I have asked Mike to put his report on our website so it will be easily found in the future. He pretty much showed that Vaughn was right at least qualitative. (The direction of the deflections could be controlled by the position of the defect when the bullet leaves the muzzle.) I don't believe, but could be wrong, that he would claim that he confirmed that the equation predicts the amount of deflection because his defect making wasn't precise enough. My guess is that it could be proven.
This isn't news, Mann showed that he could cause repeatable deflections in the same amount and direction by having the defect in the same position i.e. 12 o'clock 110 years ago (page 216-220 in “Bullets Flight"). I don't believe he attempted to quantify the deflection but he understood why it happened. I think the reason a doughnut didn't show up in your testing is that the dispersion of the defective bullets overlapped with the dispersion of the good bullets. If the load had been more accurate and/or the defects had been bigger I think you would have seen the doughnut. An easier test would be to just go for two groups or an eight shaped group by orienting all the defects the same way.
John
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Joe,
When you argue against physics (assuming the assumptions and calculations used are both correct) you have usually saddled the wrong horse.
Sometimes opinions are clothed in mathematics and/or physics to convince the less nerdlike.
Doughnuts can be shot with unbalanced bullets IF the rifle is accurate enough and the unbalancing (defect) is big enough -- if you rotate the position (1 to 12 o'clock) of the defects as it leaves the muzzle. Larry Landercasper (the guy with the 25 shot group I used in TFS #229) has done just that with his rimfire rifle. I believe it was posted on this forum back when he posted the 25 shot group but I am not sure. I have asked Mike to put his report on our website so it will be easily found in the future. He pretty much showed that Vaughn was right at least qualitative. (The direction of the deflections could be controlled by the position of the defect when the bullet leaves the muzzle.) I don't believe, but could be wrong, that he would claim that he confirmed that the equation predicts the amount of deflection because his defect making wasn't precise enough. My guess is that it could be proven.
I'm looking at Larry's group, and it doesn't look like a doughnut to me. Nor a cruller. It looks like a conventional randomly normal group. We went around on this before, I'm having deja vu. Or high blood sugar.
This isn't news, Mann showed that he could cause repeatable deflections in the same amount and direction by having the defect in the same position i.e. 12 o'clock 110 years ago (page 216-220 in “Bullets Flight"). I don't believe he attempted to quantify the deflection but he understood why it happened.
As you know, I've never been impressed by Mann's book-he should have stopped with the bone cutter and gone to Bermuda. His writing is as bad as Keynes's, and his sample sizes are tiny. In page 216-220, abut mutilated bullets:
Test 130, Aug. 11, 1903 12 shots
Test 131, Aug. 11, 1903 15, 8, 5, 5 = 33 shots
Test 132, Oct 13, 1902 9 shots
Test 133, Sept 6, 1902 8 shots
Test 134, May 20, 1903 8 shots
Test 135, Aug. 30, 1902 6 shots
Test 136, Sept. 6, 1902 5 shots
81 shots in ~ a year. I commonly shoot more shots than that on one trip to the range. And I'm frequently not sure the data from my shooting SUGGESTS anything, much less PROVES anything. Franklin didn't prove anything to me in these pages-but I was interested to see the Leopold's remark about “hollow groups".
I think the reason a doughnut didn't show up in your testing is that the dispersion of the defective bullets overlapped with the dispersion of the good bullets. If the load had been more accurate and/or the defects had been bigger I think you would have seen the doughnut. An easier test would be to just go for two groups or an eight shaped group by orienting all the defects the same way.
I can't find my many-shot non-doughnut-shaped group pictures, but there were NO good bullets shot. Try that 50 shot test RF in your tunnel.
John
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Joe, I agree completely that opinions are sometimes clothed in math or physics or worse. It is good to have your B. S. detector turned on.
Sorry for being unclear. i wasn't referring to Larry's 25 shot group which as you point out is just a normal group -- no bad bullets. Maybe the other target was never posted and he just sent it to me. He shot a few bullets with holes in one side orienting some defective bullets 180 degrees from the others along with some good bullets. The defective bullets landed on opposite sides and clearly out of the group of good bullets in the center. Hopefully pictures of that group will be on our website.
OK. I dismembered your test procedure. I will modify my guess as to why you didn't get a doughnut. If the metal removed was on only one side of the bullet, not enough metal was removed to “throw” them out far enough.
OK. I will try to shoot a doughnut if I can find a way to make a uniform defect, although i can't be sure of orientation in my bolt actions so the donut (if I get one) may be fat on one side.
John
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ahem ... pay attention class .... about 2 years ago i clearly mumbled that ::
some fliers fly INTO the center .
as for other mysterious bullet behavior ::
remember :::: NO RELIGION DISCUSSIONS !!
ken
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When you post Ken I am not only paying attention but have my pencil and notebook to write it down.
Yes some fliers fly INTO the center. That is why if you have a load that will average 1 moa and shoot some unbalanced bullets that deflect the bullet on average 0.2 moa, you do NOT get 1.2 moa groups but something much smaller as joe and mtngun have pointed out.
This is ONE of the reasons that defects don't have as bad an effect as we imagine.
OK no religious explanation for fliers but UFOs and the Easter Bunny are prime suspects.
John
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John, You forgot Santa Claus and the Great Pumpkin.
B.E.Brickey
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