I've noticed that Lyman reloading manuals state selected "Loads shown in bold designate potentially most accurate load."
Any ideas how those "potentially most accurate loads" are determined?
Loads shown in bold designate potentially most accurate load
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I've noticed that Lyman reloading manuals state selected "Loads shown in bold designate potentially most accurate load."
Larry, has it nailed. Last time I talked to Tom Griffin, editor of their books, they were still just doing internal ballistic data. Also starting loads are 10% less than maximum loads, generally. They don't actually shoot for minimum loads, just a calculation.
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Lyman CBH #3: Reloading Data Introduction chapter, page 123;
When a load is noted as such in the data tables proper, it means that a given combination of components produced the most uniform internal ballistics of any load tested utilizing that particular bullet design.
Unless noted in "Comments", the accuracy load was not fired at targets. The load, however, does have a high potential - assuming all other external factors or optimum - for producing outstanding accuracy since uniform internal ballistics are critical to accuracy on target. You cannot have one without the other."
At one time Lyman also did test fire the rested loads on their 50 yard out door range. The range was closed many years back.
Concealment is not cover.........
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I would like to respectfully disagree with some of the advice offered by 4in1 in the post above.
“Then try different powder charges, a grain at a time, start low, go up, and shoot at least 3 shots per load. You will see a change in groups as you change loads.”
In my opinion, this procedure, along with its following paragraph will not get you to an optimum load although you may be able to find and eliminate truly horrible loads, and it doesn’t do any harm. The fly in the ointment is that judging much of anything on one three shot group is an exercise in misdirection.
You will indeed see a change in the groups as you change the powder charge. The problem is that you will see equally substantial change in group size and shape if you DON’T change the load at all. So, thinking two consecutive three shot groups are indicating a trend is a very iffy assumption.
You don’t have to take my word for it. A simple test will show the wild variations in a string of three shot groups. Shoot a string of five - three shot groups with the same load and look at the ratio of the largest to the smallest. The ratio will vary of course from one five group string to the next five group string. But if you persist in shooting such strings with the same load you will find the AVERAGE ratio of largest to smallest group within several five group strings tending toward 2.5. Five shot groups aren’t a lot more consistent and five – five shot groups will on average produce a ratio of 1.9. This is true whether the groups average 0.15” or 1.5”
The procedure suggested above is the one that Tony Boyer uses to “tune” his loads to a barrel. Tony is the greatest short range JB benchrest who ever lived. So, I’m sure it will seem presumptious for a lowly cast bullet shooter to doubt the great man. But even Tony Boyer can’t shoot three shot groups that don’t vary wildly from one group to the next. I believe he is kidding himself in trying since his elaborate tuning exercise is based on the shaky assumption that a one three-shot group is a reliable indicator of what a series of such groups with that load will average.
Theoretical is an understatement. Back when I was young and dumb, there was no internet, and nobody who shot well would pass on his secrets, you looked at this and took it for gospel. What a farce. Fast forward a number of decades, and it still holds true for many I suppose. If one assumes they have a respectable rifle, good barrel and chamber, and the ability to shoot off a rest in a consistent manner, much more can be achieved.
Accuracy boils down to vibrations, and no two guns are the same. If you want to seek an accuracy load, you have to test a number of powders. Using the same bullet sized and prepped. No two powders burn the same in your gun. I start at a seating depth where the bullet is in contact with the rifling, no jump, but a mark on the bullet it has engaged. Use this as a start. Then try different powder charges, a grain at a time, start low, go up, and shoot at least 3 shots per load. You will see a change in groups as you change loads.
Try another powder, same method. Keep your targets. Try another powder. Let the targets speak for themselves. When you have something narrowed down, then work on seating depth. Go in .005", then .010". Go back to the starting point, try .005" off, then .010". Let the targets speak for themselves. Don't believe what you see in published match results. It might not work for you.
It takes time and powder/primers/lead. But to find what you gun likes, it takes the effort. All this assuming you are keeping the barrel clean during all this.
4 in 1'
I didn't expect you to agree with my post, but this isn’t an issue of just opposing opinions. The fundamental fact my argument is based on is not a theory or an assumption. It a fact based on statistics. If you shoot strings of five-3shots as I suggested, you will find that ON AVERAGE the biggest group in a string will be about 2.5 times the size of the smallest. This ratio of largest to smallest will of course sometime be smaller and sometimes larger. Tony’s own groups in his book often vary over 100% from one group to the next with only tiny changes in load or seating depth. This large variation from one three shot group to the next makes size and shape of any one three shot group much too erratic to depend on for anything but the crudest preliminary culling of very poor loads. No elaborate procedure involving tiny changes in powder charge and seating depths and making the judgement calls based on only one single three shot group of each combination can change this inconvenient fact.
We do agree on some things. Uncritically swallowing what has been passed down from successful shooters as gospel is a farce as mentioned in your first post. Such pronouncements and procedures should be looked at critically and the assumptions, both said and unsaid, should be examined. I also agree that testing is the only way to find the best load. It is also hard to disagree that there are differences between cast and jacketed bullets.
I’m not sure exactly what you mean when you claim that in JB benchrest “you can hang your hat on every shot.” But I hope you don’t mean that the laws of probability and statistics don’t apply. The groups are smaller which may give an uncritical shooter the superficial allusion that their groups don’t vary as much or don’t have the same percentage of “fliers” as cast bullet groups, but measurements say otherwise. Look again and think about the experimental 25 shot group by Lancaster in one of the articles I sent you.
You have demanded that I confess how I think one should find a good load. I plan to work on an article suggesting a general process for finding a good load after our nationals. In the meantime, I will say that I depend on single five shot groups to weed out the really poor loads and then depend on the AVERAGE of an increasing number of five shot groups as the differences between competing loads shrink. I also don’t claim to find the perfect load or reach the 95% confidence level because for small difference between loads that would take an impractical number of groups. In other words, my approach is similar to those described by Spindrift and Squid Boy in the posts above.
I do not want to get into a he said-she said. My whole method ( is what Tony Boyer uses, and many others) of shooting 3 shot groups with varying charges and seating depths is a first step in weeding out what your gun and load likes or dislikes. It will clearly show where you need to go. I shoot using a Culver measure, and my increments are one full number, not a grain, but close to a grain. You shoot the method I describe, I can guarantee you will see a path to follow. If what you see is good enough for you, then shoot 5 shot groups, multiple 5 shot groups if it suits you. You should, you need to prove it.
I cannot stress enough to test different powders. Some work, some are complete flops. You have to start somewhere. The method I show gives a quick method of shooting different powders, and seeing what works.
If a powder, at a normal velocity (1800-2000 fps) does not show promise with the bullet touching the lands, move on. Just because match results show it is popular, it has to work in your gun, not theirs.
To another point, most people who shoot jacketed short range benchrest, have a gun that has been built by very reputable gun builders using the best components. The gun's capabilities are there, you have to find the key to unlock that door. Testing is the only way. When I say, "you can hang your hat" on a shot, I mean the anomalies of shooting a cast bullet aren't there. Weight, voids, balance, etc. are pretty much non-existent with quality jacketed bullets, so each shot can give honest reliable feedback.
How many times does a cast shooter make a shot, watching flags, seeing a very stable condition, and the shot goes opposite from where it should and cost you a point? That's part of this game.
Sorry for the long delay in getting back with what I promised. Our disagreement boils down to: can a single three shot group be trusted to predict the long term performance of a load as Mr. Boyer does in his final fine “tuning” for the very best load for that rifle and barrel, as he advocates in his book?
I claim that three shot groups can’t be trusted for such decision making because they aren’t repeatable. The next one is likely to be much different. A string of 3-shot groups will vary so much from one group to the next that it will be obvious to any open-minded shooter that a single three shot group cannot predict the load’s match performance as Boyer’s tuning method depends on. You said that I ”have no idea if this is true or not”. I believe I do know that it is true..
You claim that Boyer’s tuning method is valid because you can “hang your hat” on his individual shots and single three shot groups because he shoots in the “jacketed bullet benchrest world” and not the “cast bullet world” where there are more complications. I believe that groups in the jacketed bullet benchrest world vary about the same from group to group as groups in our humble cast bullet world.
The only way we can resolve this difference of opinion is to look at strings of three shot groups fired by the same load and under the same conditions with rifles similar to Boyer’s
As promised, I shot a series of ten three-shot groups, (10.5 pound 6PPC rifle using the same exact load for all ten groups, 68 grain Berger bullets, WSR primers, and 25 grains of H322, seated so the bullets were 0.010 into the lands when chambered). I made no effort to adjust for changing wind conditions just as Tony insists you should.
The first two groups were carelessly shot before parallax in the scope was adjusted properly and should be disregarded as not quite the same set up as the following eight groups. The eight groups averaged 0.21 inch. The groups are very small, by cast bullet standards, but vary about like cast bullet groups – just as statistics says they would.
As an experienced JB benchrest shooter I have no doubt that your string of groups you post will average much smaller. We will see if all your groups are all about the same size and shape when you post them.
great stuff John ... thank you.
.. and remember that this error also applies to sighting-in ... at our local range i am lately seeing more and more hunters shooting just one of their precious $3 factory rounds to establish their " perfect " zero ...
good thing Iowa deer are real big ... ( g ) ..
oh:: good shootin ... dang ! ... i goota build an akrit gun ...
Those groups might not win a bench rest match but they are not that bad. The numbers tell me that the mean is .256" and anything averaging around a quarter inch isn't that bad in my book. The SD is .134" for ten groups with an extreme spread of .490". There is always room for improvement but I for one would like to see some other "better tuned" groups just to find where this is going. I don't have a jacketed gun that will beat these groups at the moment so I will just stand by and watch. Thanks, Squid Boy
"Squid Pro Quo"
I was just trying to make my argument as effectively as possible so you and others could see my point of view. I am sorry that you thought I was condescending.
I feel strongly that one of the faults we shooters have is trying to draw conclusions from single five, or ten shot groups. So when you recommended making judgements based on single three shot groups in your first post. I didn't think your advice should stand as the last word, and disagreed. This is a forum after all and worthless if people can't disagree.
Not being a competitive JB benchrest shooter shouldn't disqualify posters from using logic and evidence to disagree with someone who is.
We agree on one thing. Continuing this discussion is probably not productive.
The disagreement between myself and others on this thread about whether a single a three or five shot group is a reliable basis for making decisions about the load involved is unresolved. Some may think the discussion has gone on long enough. But this isn't just a difference of opinion on something that can't be proven by evidence, like which color is most pleasing to the eye, where it makes sense to agree to disagree and drop the issue.
This is a fundamental issue for shooters interested in rifle accuracy and an open forum is a good place to air different views and present evidence to support your position. We should try to find out whether single three or five shot groups, if very small and shot with a "tuned" load, are reliable indicators of the future performance of that load. If this is true, it will save a lot of scarce primers and powder in load development. If three shot groups are unreliable we should stop using them to avoid being led astray while wasting primers and powder
I have suggested that a string of ten three shot groups where all the groups are virtually identical or at least about the same size, as some have claimed possible, would be powerful evidence that three shot groups could be relied on for the final tuning of a load. However, no such string of groups has been presented.
I have assembled evidence from match reports and other sources to support the argument that three or five shot groups are not reliable enough to base decisions on and presented it in articles in Fouling Shots #274 and 275.
I urge further discussion on this important issue especially by those not convinced by the TFS articles. I believe that we will have better luck if we stop depending on single groups for decisions but I have been wrong before.
So it is all entirely theoretical. Similarly I could theorectically catch the eye of Cindy Crawford. BAHAHAHA.
Cheers from New Zealand
Measuring or evaluating the accuracy of a certain load is fundamental to our hobby. Yet, there is no clear consensus how this is done. This is one of those subjects that is much more complex than it might appear, on the surface. We venture into the realm of statistics; variation, significance, statistical power.
Somewhere (don’t remember where, might be this forum) I read a treatise written by a statistician, who was also a shooter. The subject was accuracy evaluation, number of shots and statistical power.
The more shots fired, the more information you gain-naturally. But, in practice, we’d like to know few shots with every load we can get away with, yet harvest reliable information. Shooting 100 shots with every load in the ladder is just not practical. This statistician/shooter argued that 7-shot groups was the optimal compromise.
Personally, I shoot 5-shot groups- mainly to segregate horrible loads from potentially good loads. The potentially good loads are tested next time with 2-3 5-shot groups. If the load is still good, I shoot 5 groups of 5 shots the next time, and consider the average group size the «load accuracy».
You may be talking about something I wrote some time back. I wrote in another thread about a statistician who claimed through math proofs that only seven samples were required to get the results needed for a test. I admitted being lost with regard to the math he used to prove his point but I never forgot it. However, seven is not the handiest number when testing ammo. Five or ten makes more sense because of how an ammo box is divided if nothing else. Plus, you always end up with an odd bullet or two out of a box. I load and shoot ten because it covers the value he proposed. But also to make it easier on myself. In spite of all that I think several groups are required to get good data. I will reshoot "good" loads over a period of weeks or months, even years, to verify the point. In my opinion, one thing is for sure, you will find what doesn't work fairly easily but fine tuning the best takes time and effort. Thanks, Squid Boy
"Squid Pro Quo"
Statistics indicate that 30 samples are needed to have confidence that the sample correctly represents the population.
Right. So I shoot 5 shot groups in the wider spaced ladder and 7 or 10 shot groups as the rung spacing narrows. That is enough to compare several loads - showing the trend of getting wider or narrower. Repeating the 10 shot groups around the selected load verifies it. What is practical? That depends on how OCD one is.
Remember statistics is a method to save time and get close to an answer without undue repetition. The first statistics was to put a black sheep with your 99 white sheep and at night, look for the black one. If you don't see it, you probably have a bunch of white sheep gone too. Otherwise you had to count the white sheep each night to find out your losses. Analysis of Variance (ANOVA) attempts to help us with things group size, differences in treatments, etc. However, it only gives a confidence level and even 99% has some variation. Would I bet my life on 99%, absolutely, 95% sure, hell people try to stay alive at 50% or less. In my younger days, you needed a Mainframe computer to do it. Now I'm sure there is an app for your phone.
The entire use of statistics is to get the most information out of the fewest iterations (shots). Remember every shot is an individual, sure the case may be the same (if it is resized the same). But everything else is a variable, no mater how you classify it (including the shooter). Even the rifle is changed, with each shot doing something to the bore. I'm sure all of us have experienced a load which shoots fine one day, and less so another time.
If you superimpose all the three round groups, you will probably get a normal distribution and no one load will be the keeper.
Always fun and it beats a good day at work!
4 in 1,
I know that your intentions were to be helpful. However, the conventional thinking by serious CB shooters is NOT to take loads out of a book, although that may give a starting place. Most CB shooters I know shoot groups while varying loads but usually with 5 or 10 shot groups.
I think our argument has gone about as far as it can until one or both of us post shooting tests to support our positions. The basic cause of our impasse is disagreement over whether strings of three shot groups of the same load fired under identical conditions vary wildly or not.
From my experience and from the advice of a statistician I believe to be competent, three shot groups usually vary a lot from one group to the next. The extent of this variation is illustrated by my contention that if you shoot strings of five 3- shot groups with the same load, the largest group in the string will tend be about 2.5 times the smallest. In some strings that ration will be smaller and in others it will be larger than 2.5. Adjacent groups will often vary by 100 percent.
In response you say: “You have no idea if this is true or not. I have done it.” This ability of Tony and his disiples to shoot three shot groups that don’t vary much, if any, apparently because the short range jacketed benchrest world is a different world from the cast bullet world.
To solve this impasse, we need evidence. I propose we both provid some based on actual actual strings of 3-shot groups. I will try and dig out some from strings I have already fired. I have asked you to shoot ten three shot groups with the same load on target sheet, as Boyer does, but with one load. After the nationals I will fire ten 3-shot groups with my 6PPC and post them.
Talk is cheap. How about some evidence? Please show us a string of three shot groups fired with the same "tuned load" that is so consistent from group to group that any one of the groups could be used to predict future performance of the load as Mr. Boyer claims to do.
Ten consistent groups would be a fairly easy way to prove that your are right. And when you do, I will admit I am wrong. If no such string appears any fair minded shooter will have to assume that you can't do it.
I'm sure our readers would also be happy to see a string of three shot groups that you have fired with one of your properly tuned loads so we can all admire the consistency in size and shape.
I don't think an apology is called for. I suspect it has been interesting to some, and if not, it is easy to avoid.
I have several friends who shoot JB benchrest, so I realize that most JB benchrest winners do exactly as you say. What you don't say is that the vast majority of the losers also go through this same ritual, based on the fallacy that you can tell if a load is better by looking hard at ONE THREE SHOT group. If you get a bunch of shooters all doing the same silly thing, one of them will win and be convinced that the silly thing helped.
What you have offered as proof is "everybody does it". This tells more about how these shooters follow the leader than whether any one thing they do is needed, or helpful. At one time, most winners in CBA matches indexed their bullets and cases. The shooter who owned most of the records in the early years used only one case. One of the very best current schuetzen shooters indexes his bullets, cases, and PRIMERS -- and wins. Practically none of recent CBA winners do any of these things. Doing something useless and winning doesn't show that it was useful. I believe this is simple logic that most can understand.
What we have here is an "The Emperor Has No Clothes" situation -- i.e. people blinded by the Emperor's position. If you will just shoot a series of three shot groups with your "tuned" load, measure them, and think about it with an open mind (this last part is important) you will be able to see that Emperor is buck naked.
I probably never will be a Benchrest shooter. I do enjoy plinking and participate in local CBA shoots. I have attended the NT more as a shooter not a competitor. With me cast bullets seem to have a mind of there own. Just when you think you got something working you go to a match and find out different. I collect targets from practice sessions. If it worked last time out I try the same thing next time out. After a period of time you begin to find some promise that takes you back to make a fool of yourself. Oh well what else will do.
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