How to interpret Standard Deviation and Extreme Spread on reloads?

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olesmokey posted this 31 March 2014

So can anyone recommend some good reading material on how to properly interpret  the figures that my Chronograph spits out when Im shooting my handloads across it.?  I never have read anything authoritative on the subject. Perhaps if I did I might not have to ask so many questions. For example when shooting a set of loads using published data with slight increases in powder charges and the ES and SD  suddenly double or triple from one load to the next higher load with no increase in velocity or even a drop in velocity what does that mean? Thanks Bob.

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joeb33050 posted this 31 March 2014

  1. CHRONOGRAPHS AND STATISTICS               Many chronographs calculate both standard deviation, (SD), and extreme spread, (ES), of a string of shots. ES and SD measure the same thing, the variation in the string of shots.   (Multiply ES by a factor and get SD. Multiply SD by a factor and get ES. These factors vary as the number of shots in the string varies. For 5 shots, ES times .45 = SD; SD times 2.2 = ES. If multiplying your chronograph ES and SD by the appropriate factor doesn't give you the SD and ES, then you haven't fired enough shots.)               So, forget ES, it's not as good a measure of variation as SD.               SD measures the variation in velocity. An SD of 20 is twice the variation as an SD of 10. We might expect that if velocity varies less, then accuracy would be better. Lyman's later Reloading Handbooks recommended loads are based on that assumption. Lyman is wrong, because the expectation that (slightly) lower velocity variation means (slightly) better accuracy is wrong. It looks true, it should be true, it isn't true.               So, forget ES, and remember that SD doesn't have much to do with accuracy.               The biggest problem with getting information from chronographs is that not enough shots are fired in a string. A minimum of 10 shots should be fired, with velocity measured and averaged. With less than 10 shots, the average velocity is probably not very close to the true velocity. (The “true” velocity is the average velocity of a zillion shots.) More shots fired, measured and averaged is better.                The second biggest problem is “data trimming". Some chronographs allow the user to delete velocities in a string of shots. With velocities of 1403, 1399, 1417, 1410, 1406 and so on, a velocity of 327 or 4724 should probably be deleted. A velocity of 1328 or 1472 is another matter-they look odd and out of place-they probably should NOT be deleted. When in doubt, don't delete.  

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joeb33050 posted this 31 March 2014

olesmokey wrote: So can anyone recommend some good reading material on how to properly interpret  the figures that my Chronograph spits out when Im shooting my handloads across it.?  I never have read anything authoritative on the subject. Perhaps if I did I might not have to ask so many questions. For example when shooting a set of loads using published data with slight increases in powder charges and the ES and SD  suddenly double or triple from one load to the next higher load with no increase in velocity or even a drop in velocity what does that mean? Thanks Bob. For SD go to the web under “standard deviation".For ES go to the web under “range", and “range as estimator of standard deviation" For example when shooting a set of loads using published data with slight increases in powder charges and the ES and SD  suddenly double or triple from one load to the next higher load with no increase in velocity or even a drop in velocity what does that mean?  If you fired and averaged velocities for less than 10 shots it probably means that the estimates of ES, SD and average are way off. If you fired more than 20 shots it probably means that ES and SD jumped. It is EXTREMELY UNLIKELY that within the bounds of published data the ES and/or SD jump double or triple with a slight charge increase. 

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Ed Harris posted this 31 March 2014

To attempt a brief and simple answer to a complex question: Working up “accuracy” loads over a chronograph, and chasing the numbers, instead of shooting groups on paper is a distraction.  One ten-shot group on paper tells you volumes more than reams of chronograph paper.

Once you have an accurate load which gives repeatable and predictable results, THEN is the time to chronograph it, so that you know about where that “sweet spot” is, which gives you some hope of finding it again when you change powder or primer lots, or the phase of the moon changes......

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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onondaga posted this 31 March 2014

I agree with Ed! Velocity Extreme Spread numbers have no emotional or mathematical relation to group size with a load that has a broad sweet spot. That is the load I look for.

I think a simple google search for the definitions of Standard Deviation and Extreme Spread in scientific data will help you understand, but the paper results are more important.

There are various ways to measure group sizes. My favorite spit out by the free “ON TARGET” software is Avg to Center.  The numbers are smaller, they tell the distance of shot centers to the group center in thousands of an inch and that is why I like it best! The free version of the program also spits out MOA data and saves scanned picture files with all calculated data. The paid version, cost is $11.99,  for “ON TARGET” will print the saved files.

ON TARGET: http://www.ontargetshooting.com/>http://www.ontargetshooting.com/

You only need a scanner that is compatible with your computer for this program. Watch the demo video for the program: http://www.ontargetshooting.com/videos/ontargetdemo2.html

Gary

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corerf posted this 31 March 2014

From a performance perspective, “I Personally” can't simply ignore working a load into sub 2 digit ES. I have no reason to focus on it, especially if a cartridge will shoot tight groups regardless of what I do.

But when ES is at 4 or 5 fps, well it becomes very automatic that a true one hole, one bullet diameter group will likely emerge.

olesmokey:

I believe we all may have overlooked your question a bit.

The ES and SD are auto calcd over a string of shots. Your chrono “may” be calculating over the entire length of your shooting. So if you shoot 5 at 40 gr of 4895 and you move to 41gr, continue shooting, the ES and SD are going to average over the new load and the old load. Bad deal, math is no good.

Like the economy calculator in a vehicle, when you fill the tank you must reset the fuel consumed, the MPG and your best to reset the trip odo. Now the math will only be applied to the current batch of fuel and the current full tank and driving conditions.

Likewise, you must reset your chrono buffer and start a new string fresh each time the load dynamic is changed. Then you will get a fresh unique SD and ES for that load value. Archive that data, set aside.

Reset for next load change, shoot, log and repeat.

later then you analyze the data and can directly compare load for load the SD and ES, with meaningful outcome.

The lower the ES (Extreme Spread of velocity) the tighter your vertical deviation will be. If you can match a target physically with the ES/SD data, you should be able to physically measure the improvement, if your ability to hold is not compromised between targets.

I could care less about SD! ES matters as when I get 3-4 fps ES over 10 shots, that is money in the bank!! If I do my part, the load is a laser beam of unparalleled performance. My 445 SM Encore load is just that, sub 10 fps, all shooting conditions. All I cared to see was the ES (studied by me actually looking at the 10 shot strings), not looking at auto calcd stuff. My chrono will print if I provided a printer and auto calcs, but I dont care. Im old school, I log each shot by hand in a book. Then I study when at home and compare target group size with the ES.

Then I can see the break as well. When a HIGHER ES (say 10-20 fps) makes no difference in group size. That gives me latitude to not fire a perfectly formed cartridge with scientifically measured powder charge and still drill one shot after another in the same hole. The group size should relate directly and proportionately with ES. Higher ES, bigger hole.

This is how I work, not necessarily the right way or how others work. I have found it “works for me” and I have fired many loads that never achieve a LOW ES and of course, never achieve my desired accuracy.

So I hope that answered your questions along with Joe B giving you then math end that the SD is derived from.

Joe stated the longer the string that is shot and calculated for, the more accurate the ES and SD will be. I shoot 10 rounds. I kill animals, thats the intended target, not paper. Since I dont compete, very long strings dont help me. For a BR shooter, they do.

But you must reset!!! Dont forget to RESET when your load changes. That may be where your getting odd duck outputs.

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John Alexander posted this 31 March 2014

olesmokey,

I chronograph thousands of rounds per year, but only because I shoot that many over a permanent chronograph set up in my tunnel.  So it is easy and I am always curious if it will show something interesting.  Sometimes it does such as velocity consistency increasing for several shots after a bore cleaning for some loads. Hmmm I wonder why that load and not another???   I have tried many times to see if I could find a correlation between SD or ED and group size and have never seen it.  Groups with a small SD and ED are often much larger than the next group with a much larger SD and ED.  So I agree with Joe, Gary and Ed that chasing SD or ED isn't the way to find the best accuracy.   John

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corerf posted this 31 March 2014

JA: With the greatest of respect-

Not sure how extreme spread couldn't affect a group size. What does 50 FPS do to a bullet at 200 yards?? Nothing?? What is the point of a BR shooter striving for LOW ES? It makes no difference? Thats nonsense. At 50 yards, sure I cant measure squat. Gravity needs a period of time to act on a projectile. At 200, you bet gravity has done its job. Simple trajectory math proves that it MUST affect the vertical impact point. It alters trajectory, dramatically and is amplified at distance.

if I have misunderstood your PM, please advise.

Is this information only good for cast bullets? Id like to query a 1000 yard competitor if they would be ok with a high ES. I don't shoot 1000 so I have no true hands on data. But Im willing to bet that 50 fps at muzzle, makes for a solid 1 inch change at 1000 yards---- its just math and physics!! They are not arguable. I will absolutely stick my skinny neck out here and say that as a prediction, the super shooters at 1000 have low ES and the guys with less than stellar consistency, have high ES. CAN A SHOOTER make a tight group with HIGH ES?? Sure. With ZERO outside forces other than gravity acting on projectile, lower ES means “shorter” group, period. I didnt say they dont pull every other shot, nor fail to hold over or dope correctly, or get beat by wind in the mean time. I've had days with no wind at 100, there I can tear a sheet of paper in half with vertical stringing like a used a 1/4 inch wide blade to cut it. Relating directly to HIGH ES. When ES dropped, the vertical string shrank in height.

Same day, a 3 inch group and a 5 inch group. Which direction did group open and when? If ES stayed the same, Ill guarantee the group opened sideways!!

Chasing ES is chasing consistent loading practices since one is the product of the other. If its not greatly important than we should all shoot competitively with range p/u mixed bag brass, unsorted, untrimmed and unsized. After all it wont make an impact on group size, since it only affects ES and ES has no measurable bearing on group size.

I believe that is what your conclusion states.

If this only relates to cast and the load performs poorly and has a 6 MOA capability, I agree that ES/SD/FPS/CIA/MPG/ and FBI all matter not. You might as well put the bullets in a basket and fling them from 3 feet away. When you have a performer (cast or otherwise), a bullet that fits, a barrel that shoots, a cartridge that has a load response narrower than the Grand Canyon, then ES absolutely matters- paramount. 9 Gr of Red Dot in an '06 case with 190 gr cast, nope thats not going to fly. A load with .2-.3gr sensitivity in velocity, you'll read the paper like a Bible- truth clearly illustrated.

I have no emotional attachment (not sure if directed at me or only Gary), I hate the chrono, takes time to setup and lug around. But If I have an ML that does SUB 1 MOA out to 100 yards with a round ball (that presents LOW ES on chrono vs HIGH ES with a net loss of 1 MOA), then surely I should take the time to strive for LOW ES with a more modern launching system. My several year old Black powder production thread here on CBA forum that had groups illustrated very well the correlation of ES and group size. It wasn't a perfect study, but it did read pretty clear, ES and Group size do interact. None of this matters if your intended performance is greater than 1 MOA. Any modest load variation will alter the group size sufficiently enough to meet the intended performance criteria.

Please advise. Im sure I have misinterpreted something.

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onondaga posted this 31 March 2014

http://www.castbulletassoc.org/view_user.php?id=7625>olesmokey:

My earlier answer mentions a “Broad Sweet Spot” trumping or having more relevance to group size than ES does. I am sticking with that and wondering if you truly understand what a broad sweet spot is?

A broad sweet spot produces a small group with a number of various but close charge levels. We search for sweet spots or visible groups of impacts on the target when shooting a string progressively increasing or decreasing charges in the  traditional “ladder load” method that is pretty commonly misunderstood and the term Ladder Load is frequently applied to a variety of load testings that are not ladder loads in the traditional manner at all.

So when I say that a broad sweet spot is more important than ES, this is something you can prove yourself. If you do chronograph testing while shooting a ladder load test you will find that the sweet spot that is sufficiently broad is found to contain a wide spread of velocities that do not effect the sweet spot at all.

to understand what I am positing here be sure that you truly understand what the traditional “Ladder Test” encompasses. This is shooting at 1,000 yards with a progression of charge increments and each shot is  identified only by the charge to show where a cluster of hits exists and appears as a group but every charge is different. The cluster is the “SWEET SPOT” that is not sensitive to charge or velocity.

You can find a nice review and outline showing the classic 1,000 yard  ladder load method here:

http://www.6mmbr.com/laddertest.html>http://www.6mmbr.com/laddertest.html

This is an interesting read that takes away the misunderstanding, misinterpreting and misnaming of ladder load testing as a method for long range load evaluation and locating a true SWEET SPOT. Velocity differences from shot to shot are not relative to this method of testing at all. The cluster that is found is what is relevant and shows the range of charges that defines the SWEET SPOT and how broad of a range of charges exists that the SWEET SPOT encompasses .

Gary

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onondaga posted this 01 April 2014

"slight increases in powder charges and the ES and SD  suddenly double or triple from one load to the next higher load with no increase in velocity or even a drop in velocity what does that mean? Thanks Bob."

This means you are far away from the sweet spot and the charge area you are investigating is a accuracy looser area for your bullet where there is no broad sweet spot. So either the powder was a bad selection or the charge area you hoped would be accurate will not be and is somewhere above or below where you are at..

Some powder/bullets will exhibit multiple nodes of accuracy, some powders/bullets only have one charge area node that shoots well. These things are up to you to find out for your rifle, your bullets and your loads. Nobody else's loads are valid for your stuff when you are looking for a sweet spot.

Gary

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joeb33050 posted this 01 April 2014

corerf wrote: JA: With the greatest of respect-

Not sure how extreme spread couldn't affect a group size. What does 50 FPS do to a bullet at 200 yards?? Nothing?? What is the point of a BR shooter striving for LOW ES? It makes no difference? Thats nonsense. At 50 yards, sure I cant measure squat. Gravity needs a period of time to act on a projectile. At 200, you bet gravity has done its job. Simple trajectory math proves that it MUST affect the vertical impact point. It alters trajectory, dramatically and is amplified at distance.

From the bench, variation in velocity does not cause the variation in elevation at the target that we would expect from trajectory calculations. My theory/explanation is that the slower bullet allows more time for the muzzle to rise, cancelling some/all/more than the expected/calculated elevation reduction. The faster bullet gets out of the muzzle before the muzzle rises as far as it would with a slower bullet. Hence, variations in velocity are self-corrected to some degree. (Pistols are well known to shoot higher at lower velocity in some/many cases.) Trajectory calculations are of great help in some applications, but do NOT describe what happens with real guns, because real guns move before the bullet exits the muzzle-contrary to some published nonsense. Pistols, such as the Savage Striker in 308 Win and Competitor in 30 BR showed elevation adjustments markedly less than trajectory calculations estimated because the pistol muzzle rises so much before bullet exit. Long range low velocity shooters are quite concerned about velocity variation. I don't know if this concern is justified or not. Certainly to 200 yards enough of us have shot enough groups to lose faith in the mathematical velocity/elevation or velocity variation/accuracy relationship.  I realize that the chronograph and spotting scope together show the shooter a picture that is hard to accept-but it be what it be.

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John Alexander posted this 01 April 2014

   corerf,

  I don't believe you misunderstood my post.  I understand that a variation in muzzle velocity “should” enlarge a group in the vertical direction.  I have competed in 1000 yard matches but not benchrest 1,000 yard matches and so have no experience about the correlation, or lack thereof, between ES and vertical group measurements at that distance.  I will leave that for others to argue who have access to a 1,000 yard range.  My personal evidence is limited to what happens in the first 200 yards.     It is perfectly logical that, IF ALL ELSE IS EQUAL, a faster bullet should hit higher on the target than a slower one.  The problem is that when a rifle fires a lot of things are happening that we don't fully understand and have no good way of measuring some of them. ALL ELSE ISN'T EQUAL and Gary and Joe have pointed out two mechanisms that cause two shots at different muzzle velocities not to be equal.     I am in favor of trying to identify and measure those things that are obviously there but quantifying and measuring some things is very difficult. That doesn't mean that they aren't real even if we can't completely understand and measure them.  We can perform experiments to show that they are working whether fully understood or not.     I would like to see more good experimentation to learn more about the fundamentals of what affects our cast bullets but that is slow in coming.  In the meantime we have to be careful not to think that because something seems logical given our simplifying assumptions (which are always necessary) that it will actually act the way our good logic (possibly with bad assumptions) says it will.       As far as my snarky side comment is concerned -- I am sorry I made it and apologize to both you and Gary.  It was uncalled for and I will edit it out of my post.   John    

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Larry Gibson posted this 01 April 2014

"The lower the ES (Extreme Spread of velocity) the tighter your vertical deviation will be."

If you shoot much beyond 100 yards you'd better not “forget ES” because it is indeed important. As to a correlation between a good ES and SD and accuracy I, as has Dr. Oehler, found that a truly consistently accurate load will not be found w/o a good ES and SD. I have been chronographing loads for almost 40 years now and have found the only “correlation is that if the ES is within good parameters for the cartridge/firearm and the SD is within 15 - 45% of the ES the load will probably be accurate if the components are of quality and compatible.

LMG

Concealment is not cover.........

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Ken Campbell Iowa posted this 02 April 2014

ok, how about this one ...

” since faster bullets slow down faster than slower bullets ... then at some time after firing ... the faster bullets will approach the speed of the slower bullets .. “

so ... the longer the time of flight ... the less the effect of muzzle velocity variation.

if this intrigues anyone, don't call me; i will be out shooting offhand at 50 yard bean cans.

( g )

ken

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John Alexander posted this 02 April 2014

Ken,We all should probably all be out shooting soup cans but there is still a lot of snow here -- one window is completely covered where it slid off the house and snowshoes area pain and its 17 outside so it will be a while. I don't know what the others excuse is. John

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John Alexander posted this 02 April 2014

   LMG,

I don't think anybody is claiming that ES can't be important if bad enough -- just that finding the lowest ES and then seeing how it shoots is usually not as efficient an approach as the other way around. A key question is what ES is good enough.     I agree completely that if I had two loads that had the same short-range accuracy, I would choose the one with the lower SD.  But that isn't always the choice.  My present match loads have an ES of 30--40fps and an average muzzle velocity of 1,450.  That should be enough variation to show vertical stringing at 200 yards but even under ideal range conditions the groups don't show vertical stringing.  I know how to load with another powder to about the same velocity and get ESs of 12 to 18 but the average accuracy is much worse and the much larger groups have bigger vertical as well as horizontal spread at 200 yards than the less consistent load.  That may not sound logical but that's what I see happening.  So the flat statement in your first paragraph is not what I have seen repeatedly at the range.   Simple theories based on ideal (simple) assumptions are very useful but they don't always predict actual results.  This is true in any field not just cast bullet shooting.  We would like for everything to be simple and to be explained by high school physics but the world is way more complicate than we may understand. Joe, Gary, and Ken have all pointed out complications that could tend to muddy up the neat results expected by the simple theory.  A theory that came closer to explaining what actually happens on the target would be much more complicated ”€œ and we don't know how to state it yet.   I believe our differences of opinions are not because some of us don't believe that ON AVERAGE (from most rifles but obviously not some handguns) a faster bullet will hit higher on the target than a slower one -- they usually do if the velocity difference is enough.  I suspect our difference of opinion is because in most cases (reasonably good ES) the vertical dispersion at the target caused by ES is obscured by the much bigger size of the group.   John      

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corerf posted this 02 April 2014

Ill try to word this appropriately. All is stated with complete respect to all.

JA: I never said that I used ES and SD reduction to find accuracy, I said I have yet to find a HIGH ES load that met my accuracy standards, that a LOW ES load was likely to produce one hole performance, that SD to ME matters not as I log 10 shot strings by hand and work toward reducing the ES only. At no point did I say I use ES/SD to find an accurate load. I very clearly stated, I cant ignore WORKING A LOAD into sub 2 digit ES. A shotgun pattern is not a load, I did not define what “A LOAD” is. That was my mistake. A load is not an attempt (in my vocabulary), its a proven recipe!

JA: You have now mentioned that any ES improvements “could” be obscured by other load defects or deficiencies that cant be quantified. Very roughly paraphrased. This is a NEWER statement made by you.

I agree with JA!

If WE cant quantify the deficiencies and make them predictable, then the jacketed bullet performance we see today at the range and in the field is all a farse and science is bunk. Maybe WE cant quantify due to the copious factors that are difficult to isolate (especially with a cast bullet we make), but..... someone figured something out at Berger!

Joe B mentions Lymans Reloading manuals spec'ing the low ES loads as the most accurate. Joe B did not agree with Lyman. I agree with Joe B- IN PART---

Put those two statements together-

Lyman specifies that the low ES load is the most accurate- An assumption is made that the bullet/twist rate chosen could even stabilize the bullet at a particular low ES load. Or that a bore condition, barrel harmonic length, wind condition, trigger weight, shooter, visibility, mirage, correolis (spelling) effect, Bad Gas from the other nights 5 alarm chili, etc would be lumped into a shooting platform that responds correctly (as predicted or expected). Lyman MUST ASSUME THAT THE HANDLOADER WILL HAVE MITIGATED RIDICULOUS VARIABLES THAT CAUSE THE LOAD TO NOT BE VIABLE FOR OTHER REASONS. Lyman also makes the assumption that a rifle load recipe will be fired from a rifle and the performance anticipated is printed in their book. Yet we will shoot a cartridge for a rifle in a pistol (shorter barrel than test apparatus) and the HANDLOADER SHOULD EXPECT WHAT LYMAN PRINTED IS TRUE?? Of course not. OTHER VARIABLES PRECLUDE THE EXPECTED RESULT! LYMAN IS CORRECT, IF NOT PRECLUDED BY OTHER FACTORS, the LOW ES LOAD WILL BE STATISTICALLY MORE LIKELY TO PRODUCE SMALLER GROUPS THAN ANOTHER WITH LOWER ES in the same data sheet.

My statements, LMG's statements (Im guessing) are based on the presumption that “other load defects or deficiencies” have not already destroyed or hindered the productivity of the load. I believe we all agree regarding the effect of LOW ES, except certain points or references have been omitted from each thread participant, not even eluded to in some cases. Take a bent nose bullet load, bullet is 1.5 inch long, twist is 1-40, velocity is 100 fps. I cant imagine why the bullet is tumbling in flight, it leaves the barrel consistently with a MV of 100 fps, ES of 2. By golly it should be perfect according to corerf and LMG!

No, the “other defects and deficiencies” trump the effect of low ES. What are those deficiencies? They are as vast as the stars in the sky and some we cant even identify much less address- I agree JA!

Lets make some assumptions that a modicum of thought and effort was put into a load to produce viable accuracy levels prior to the search for lower ES!

LYMAN DOES!

See below-

QUOTE ED HARRIS: “To attempt a brief and simple answer to a complex question: Working up “accuracy” loads over a chronograph, and chasing the numbers, instead of shooting groups on paper is a distraction.
One ten-shot group on paper tells you volumes more than reams of chronograph paper.

Once you have an accurate load which gives repeatable and predictable results, THEN is the time to chronograph it, so that you know about where that “sweet spot” is, which gives you some hope of finding it again when you change powder or primer lots, or the phase of the moon changes......"

NOT SURE WHY this quote from Ed didn't end this thread dead in its tracks, but I for one was still consumed with “ES doesn't matter!". I offer another apology for not reading and re-reading Ed's text---

Id like to offer my final word on this- which is I believe we all (who have spoken) agree that indeed low ES is very important, when the behaviour of the load is acting as anticipated/desired according to the laws of physics and the shooting platform chosen. “Other defects and deficiencies” have not precluded the improvement that can be measured on paper by a LOWER ES.

To fully agree with JA-

I agree fully that a low ES load will not necessarily reduce a group size nor produce the smallest group for a given load and shooting platform. If LOWER ES ISN'T shrinking your groups, then there are other factors mitigating it's relevance. If this is the case, then the obstacles are not ES, but those other factors that need chasing! I offer my apology for not agreeing fully, my vision has been clouded by blanket statements that intimate LOWER ES doesn't shrink groups! I work from a standpoint, the chrono doesn't come out to play till a group is SMALL already! But unfortunately I believe my FIRST response was very well misinterpreted and taken tangent. I only wrote 2 sentences on ACCURACY and ES/SD. I then explained data stacking in a chrono buffer and why it needs reset between shot strings.

I agree with Joe and JA as to the ES not being something to chase (Initially), as mentioned above with the bent nose bullet. One must FIRST hit the paper to figure out if the ES is affecting group size. Per Ed Harris!

Im pretty sure that THIS thread got misdirected and fast from what the thread starter intended for a question. He requested an answer for WHY his chrono spits out ES and SD in radical numbers when certain things happen.

JOE B answered in the most clear mathematical way, perfectly (but over my head)- directly to the question at hand. Bravo JOE!

I believe I answered that in my first response if I understood both his use of the chrono and how his data was being stacked in it. The thread turned into a debate (by way of highjacking) over whether ES and SD matter.

I apologize for highjacking or playing my part to sidetrack this original inquiry. A new thread should be started to either continue the discussion or at least abandon the highjacking attempt.

Respectfully,

Mike

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Ken Campbell Iowa posted this 02 April 2014

sigh.

barrel vibrations.

and not just long whippy pencil barrels.

even on our 20.5 in. long 1 inch dia. 0.214 hole 22 rf ( mild excitement ) barrels ... an adjustable ( 0.001 in. clicks ) weight caused group es of about 3:1 ratio.


so possibly bullets with exactly the same mv are not exiting the barrel pointed in the same direction.

sigh.


i remember several very serious magazine write-ups of testing 15 brands of 22 rf ammo ... 5 of 10 shot groups and everything ... with beautifully tabulated results of accuracy obtained ...

BUZZZZ - NOT VALID !!

too bad a barrel tuner was not used at 20 different settings for each brand ...


at the time i quit frying my brain on this subject, the consensus among my little group of self-proclaimed experts ...( g ) .. was that weight-tuning a barrel was not the same as working thru a range of powder charges to find the sweet spot ...

sigh.


so it might be interesting to compare a load with small sd of velocity .. with one of large sd of velocity .. both with a range of barrel weight tunings ...


fwiw, in our match rifles, a good lot of ammo that shot best in one rifle ( after tuning ) would also shoot best in the next 40 rifles ( after tuning ) .

sigh.

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corerf posted this 02 April 2014

So Ken now that you have eloquently spouted platitudes and dead end statements, maybe bring the whole concept presented home a bit less condescending for those of us who have less upstairs than you, in particular me.

olesmokey wrote: So can anyone recommend some good reading material on how to properly interpret  the figures that my Chronograph spits out when Im shooting my handloads across it.?  I never have read anything authoritative on the subject. Perhaps if I did I might not have to ask so many questions. For example when shooting a set of loads using published data with slight increases in powder charges and the ES and SD  suddenly double or triple from one load to the next higher load with no increase in velocity or even a drop in velocity what does that mean? Thanks Bob.

And frankly what how does it bear at all towards the response requested by olesmokey? Why did his ES and SD radically jump during his shooting session and how should that be interpreted?  So again, Ken, your right. Velocity ES/SD/CIA/FBI--- all dont matter. Just shoot at bean cans and we will all be in Utopia.... I will start as soon as I am home from work. Eat a can of beans, then shoot in back yard with bb gun. My life will be complete as is yours. But how bout someone with your stature and experience address the actual thread question?? JA?Ed? Joe attempted to- and did. Anyone--- not still trying to push their will on others with platitudes, ready to answer olesmokey's question?? Ill start another thread called, Velocity ES DOESNT MATTER!! and let olesmokey get an answer to his question.* SighAren't pissing matches fun, I feel they probably are more exciting than an actual shooting match. SighEach platitude, another round fired down range!Sigh*

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Michael K posted this 03 April 2014

My head hurts.

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John Alexander posted this 03 April 2014

Mike,  You are right we should have stopped after Joe and Ed answered the question olesmokey asked to start the thread. Why don't we do it now. Better late than never.  John 

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