What is the best way to find the optimum load for a given rifle?

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  • Last Post 29 May 2022
John Alexander posted this 08 May 2022

A while back we had a fairly long thread going on Tony Boyer's (and a large share of the JB benchresters) method for finding the optimum load for benchrest shooting (tuning). Although the discussion centered on whether the Boyer method was a valid approach, little was said about other procedures for finding the optimum load for a rifle. We constantly hear about "working up a load" What does that mean to you? I think it would be interesting to see how we each go about this chore.

Anybody interested in cast bullet precision in rifles including match shooters and others afflicted with the compulsion to be able to shoot the smallest average groups must try to solve this problem.  How do you go about finding this load ? How many groups for each comparison? How many shots per group?  Once you have what seems to produce the smallest groups, when should the load be tested later to confirm that it is till the best?

Let's limit the discussion to only after a bullet and powder have been selected to avoid getting into the pros and cons of bullet design and the trials and tribulations of selecting a powder.

How do you do it?

John

 

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Lucky1 posted this 29 May 2022

I have to agree with John that I'd much rather spend the time shooting groups than calculating all the statistical analysis that can be generated. I don't have near the competition experience to say that every shot was a good one and any deviation was the fault of the load and my technique. If all but one or two bullets suck into a nice group my best guess is I didn't set the rifle perfectly, my eyes watered or more likely around here in SD, a poor wind call on my part. (It always blows in SD and 10 mph at 90 degrees is considered calm). Plus I'm still not retired so time spent in a fun activity is way more satisfying. This is not to denigrate those that love to do statistical analysis, more power to you guys. But I am betting retirement will be no less busy so I will probably just wander through with trial and error and a big smile when it actually goes right.

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John Alexander posted this 19 May 2022

Bryan,

My dictionary says -- The most favorable condition, degree, or amount.

In the case of this thread, or in the Boyer tuning method, that would seem to translate to the load most likely to win a match.

In the case for the most effective hunting load it might be a combination of best accuracy, killing power, and trajectory.

Just out of curiosity, since it's a common word, why do you demand that it be defined?

John

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Bryan Austin posted this 19 May 2022

Define the word Optimum

44-40 Website - https://sites.google.com/view/44winchester/chasing-the-44-40 ..................................... 44-40 Videos - https://juxxi.com/channel/4440Cartridges

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Paul Pollard posted this 19 May 2022

It is clear to me that shooters ain't statisticians, that any stats rules-of-thumb are ignored, and that life goes on. Accurate/precise guns and loads are developed, the hard way, with no well-defined plan in mind. This is a hobby, supposed to be fun. I have fun shooting, and doing statistics; ignore the stats, cast, shoot, have fun.

Statistics would be useful if we could follow a plan to use them. Whenever a discussion of statistics and how to use them comes up, it usually results in finger pointing, "my way is more precise than you way", etc. As a  person with little useful knowledge of statistics, my eyes glaze over and I dream of shooting thousands of rounds, collecting very little data of  value. 

At my work, we used a statistics program called MiniTab. It was an expensive program, but even a dummy like me would look lie a brilliant statistician. 

My approach to finding accuracy is to use process control. I preheat my mold on a hotplate and check the mold temperature before starting to cast, eventually establishing what temperature to set the hotplate at. I mix a 100 lb batch of alloy at a time and cast into ingots. The casting is done in a 20 lb Lee pot with PID control. In this way my expected weights are the same throughout. I find the temperature where the alloy becomes liquid and set my pot temperature for 100 to 125 degrees above that for casting. This allows for faster casting, usually 5 casts per minute with a single cavity mold.

This gives me a uniform bullet, but I still don't know what it takes for accuracy.

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Sevenfan posted this 17 May 2022

[quote=Bud Hyett]Empirical research to this date, but I have a 7mm BR and a 7mm-08 I want to do a structured study on. The SAECO 160 grain mold and the RCBS 168 grain mold together.

I am never sure what I know, I am restructuring my testing methodology in this coming 7mm endeavor. When you think you have the right answer, go back to see if you have the right question.[/quote]

I will be very interested in your 7mm data, most especially with the two moulds mentioned, as I will be transitioning to 7BR sometime late summer and using the exact same moulds.

A review of match reports back to ~2017 and produced only a few 7BR entries.

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John Alexander posted this 17 May 2022

Joe states:Mean radius and group size are measures of the same thing, the ratios are the ratios. It is like measuring the distance from Chicago to Denver in miles  and kilometers. Some advocate for kilometers, others for miles.

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Joe, I agree that mean radius and group size are measures (estimates) of the same thing, but that doesn't make them equally efficient. Comparing estimating methods to units of measure is not the best comparison (apples and walnuts). There is an exact constant between miles and kilometers that can be carried out to as many places as you please.  Group size and mean radius are ESTIMATES of the level of precision.  Your "constant" for converting from one to the other is also an estimate, in this case only good to maybe two places as seen in your chart.

The idea that you should be able to make a more efficient estimate by measuring all the holes seems sound whether by mean radius, two shot groups, or single shots at 25 aiming points. I'm sure there are conversion factors ("constants") that will convert the results of any of these to any other, or to group size. That doesn't mean they are equally good estimates.

==========

 It is clear to me that shooters ain't statisticians, that any stats rules-of-thumb are ignored, and that life goes on. Accurate/precise guns and loads are developed, the hard way, with no well-defined plan in mind. This is a hobby, supposed to be fun. I have fun shooting, and doing statistics; ignore the stats, cast, shoot, have fun.

=====

Totally agree. Anyway, I haven't seen evidence that the measure every hole methods are substantially more efficient than group size for estimating precision and when it comes choosing between plotting and computing individual hits vs. just shooting more groups to achieve better estimates of precision (even though a nerd) I will take shooting every time.

 

John

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joeb33050 posted this 17 May 2022

Joe,

Your table above showing that the estimated mean radius estimated by applying a constant to the 10-shot group size produced a very good estimated value of the mean radius actually calculated by measuring the locations of the ten holes.

Mean radius and group size are measures of the same thing, the ratios are the ratios. It is like measuring the distance from Chicago to Denver in miles  and kilometers. Some advocate for kilometers, others staunchly defend miles; ad hominem attacks ensue, blows are exchanged, shots are fired. Nonsense reigns.  

The same is true of ES and STANDARD DEVIATION-measures of the same thing.  

Please stop me right here if I misunderstand the above.

So if I understand, using the information from two holes (extreme spread) in most cases provides, for practical purposes, almost as good a measure as diddling around with the data from all ten holes.

Five 2-shot groups is a better estimate of precision than two 5-shot or one 10-shot groups. BUT, only if statistical calculations follow.. 

Not a very good argument for going to more elaborate mathematical means, than simple group size, to estimate precision. The idea of using the information from each individual shot is intellectually pleasing and should be a tiny bit better but doesn't seem worth the trouble when the expected difference in two adjacent groups is much greater than the error in estimating shown in your chart. In other words it makes more sense to shoot two groups rather than computing the mean radius of one.

It is clear to me that shooters ain't statisticians, that any stats rules-of-thumb are ignored, and that life goes on. Accurate/precise guns and loads are developed, the hard way, with no well-defined plan in mind. This is a hobby, supposed to be fun. I have fun shooting, and doing statistics; ignore the stats, cast, shoot, have fun.

 

John 

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Ken Campbell Iowa posted this 17 May 2022

i have been waiting for someone to mention ::

 

first setting the goal.

**************

as a plinker, my goal is pretty blah ...  bean can groups at 30 yards are acceptable ... bean can groups at 100 yards is worth entering in my log book while downtown in big smiles city. ...

******

but even lowly standards are not always easy to meet ...  often just looking in the lyman book and then loading a 1700 fps amount of fast to medium powder gets me a 4 inch group at 50 yards ...  hmmm ... up and down on the powder or different powder doesn't help .. i don't even go through that exercise anymore, as long as the bullet holes are round.

it is always the lonely ( there aren't any other rules ) Rule One :: ... it is always bullet fit.

in the old days i would make a squish die and get an occasional 1 moa screamer group from a good rifle ... now i just order another Lee $26 mold ..  ... anybody else have molds for rifles long traded off and for rifles not traded for yet ?? ...

*****

and more on topic ... when serious accuracy testing, i do aim for about 1700 fps .. try 3 different charges of same powder and 2 or 3 powders ... one 5 shot group of each  ... ( hold on guys ) ...  

pick out a few good lookers and keep loading these forever and eventually eliminate the loads that let me down .  i will never find the very best FOR SURE load in my lifetime ... i do find one that meets my goals ... or i put the rifle back in the rack, it ain't the load.

*******

i suppose you could say that one good way to develop good loads is to get yourself a good rifle.

ken, guilty but smiling plinker .

 

 

 

 

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TRKakaCatWhisperer posted this 16 May 2022

Thanks for the answer.  Verrrry interesting. I am impressed and mystified. I have never heard of anyone lapping a bore until they got better accuracy.  Do you remember how many groups of how many shots they were shooting before more lapping?

Of course if you shoot single groups of less than 25 shots and do anything, or nothing, to the rifle in between you will eventually get a group you like -- which can be misconstrued as improvement.  I wonder if this is somewhat similar reading the future in a three shot group as practiced by many.

There is no end to the interesting angles in shooting.  

John 

 

A lot of I-don't-know's  - but Bill Alexander (of the Alexander Arms) has his PhD in physics - knows his game.  Unassuming, very personable.  Has the powder company mix his own blend of powder!

 

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John Alexander posted this 15 May 2022

Thanks for the answer.  Verrrry interesting. I am impressed and mystified. I have never heard of anyone lapping a bore until they got better accuracy.  Do you remember how many groups of how many shots they were shooting before more lapping?

Of course if you shoot single groups of less than 25 shots and do anything, or nothing, to the rifle in between you will eventually get a group you like -- which can be misconstrued as improvement.  I wonder if this is somewhat similar reading the future in a three shot group as practiced by many.

There is no end to the interesting angles in shooting.  

John 

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TRKakaCatWhisperer posted this 15 May 2022

Were they lapping the bores for smoothness or dimension change? Or was it  the molds or dies that made the bullets that were being lapped to different sizes? It would be interesting to hear more.

John

 

They would take a large number of rifles to the range and test fire for accuracy.  Then each one was bore-lapped until it met spec (accuracy).  One person shooting groups, the other lapping, then do the same on the next rifle.

 

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John Alexander posted this 15 May 2022

Joe,

Your table above showing that the estimated mean radius estimated by applying a constant to the 10-shot group size produced a very good estimated value of the mean radius actually calculated by measuring the locations of the ten holes.

Please stop me right here if I misunderstand the above.

So if I understand, using the information from two holes (extreme spread) in most cases provides, for practical purposes, almost as good a measure as diddling around with the data from all ten holes.

Not a very good argument for going to more elaborate mathematical means, than simple group size, to estimate precision. The idea of using the information from each individual shot is intellectually pleasing and should be a tiny bit better but doesn't seem worth the trouble when the expected difference in two adjacent groups is much greater than the error in estimating shown in your chart. In other words it makes more sense to shoot two groups rather than computing the mean radius of one.

John 

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John Alexander posted this 15 May 2022

Were they lapping the bores for smoothness or dimension change? Or was it  the molds or dies that made the bullets that were being lapped to different sizes? It would be interesting to hear more.

John

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TRKakaCatWhisperer posted this 15 May 2022

I'm sure that he had several things in mind when developing the "factory load".  I've spent lots of range time with a fellow that helped him work up the Grendel barrels - shooting - lapping -shooting -lapping until the accuracy standard satisfied him.

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John Alexander posted this 14 May 2022

Yes, this sounds very "professional " and very labor and equipment intensive. It was also probably needed to avoid high pressure for a commercial effort. But was there any evidence that it helped find the load that would produce the smallest groups.  I doubt if precision was the first interest in the 50 Beowulf.  More equipment and more picky details doesn't mean better. 

John

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TRKakaCatWhisperer posted this 14 May 2022

PS. I was hoping I'd hear how people approach load development for cast accuracy from this post.  For instance, there's a significant amount of preliminary work that has to be occur before you can expect the fifth bullet fired on target to find its 4 teammates even if you are limited to one mold. 

...   Thanks, Bill C.

The most professional load development that I've observed was when I ran across Bill Alexander at the range (of Alexander Arms).
He was developing loads for the 50 Beowulf.  [He developed the rifle, the round [as well as the 6.5 Grendel], AND his own mix of powder.]  He was shooting groups and recording both chamber pressure and velocity as well as group size.

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Bud Hyett posted this 14 May 2022

Bud I would agree with that as far as the mold choice but even that would require hands on tinkering in the shop to finalize the fit to bore. – Yes, the mold is only the beginning. I’ve got several custom molds that have taken the same amount of work to get repeatable results.

The bore rider is the simplest design (IMHO) and even that has to be fitted to the bore either with beagling or choice of alloy. – I’ll lap a mold as a last resort.

But match reports are a great place to start for mold selection. – You have to start somewhere, set a baseline and keep good records of each change.

Powder selection is great topic and I'll start a thread specific to powder using your post if you don't mind. – Do it.

BTW did you mean N-135 or N-335 in your post? – N-135

As a disclaimer, there are many others that shoot for accuracy that do not compete. – Yes, one of the choices of accepting the Boeing offer and moving here was the opportunity to shoot.

I fully respect their knowledge and skill. – Yes, I know several people who do this. Most are prairie dog shooters seeking another hundred years for the next season.

But match reports are the only source those that do not decades of individual experience in cast accuracy. – Very useful.  

And if it’s shot and measured in a registered match its solid information (cast competitors don't lie about their equipment list like those jacketed BR shooters). – I’ve shot jacketed and found the same thought.

At this point in my learning curve, I respectably disagree with you about seating depth. – Disagreement leads to more experimentation and better collective knowledge.

I qualify that comment by saying that although I've cast for almost 30 years, and it’s only been in the past year that I tried to keep them all going through the same hole. – I started on this voyage three decades ago as the match concentration forced me to forget work problems. For five hours at a Saturday morning match, the concentration took away the work week and then I have the rest of Saturday and Sunday to enjoy.,  

Let me put it to you this way; I think seating depth is to jacketed accuracy as bullet fit is to cast. – Yes, I have the same thought.

And right behind bullet fit to throat for cast accuracy I would put powder choice. – I don’t think powder is important with reduced loads. I’ve found a rule with jacketed; when the load starts smoking at the muzzle, it is at peak efficiency. Even if not a maximum load, I quit at that point.

And for clarification could you explain "witness mark at .050". – The mark of the land on the bullet measuring .050 in length. This does not have to be even as the leade and the bullet can vary enough to not be uniform.

I came from a jacketed accuracy world where the key words were kissing and jam. – Yes, same thought.

And then we speak about thousands of an inch off of jam. – Yes, my gunsmith is a jacketed long range specialist, and we have to go through a definition of terms each time I drop a rifle off.

So, with only one powder and one mold where do you start your seating depth for bore riders? – Slight witness mark on the nose. The current move to the Remington style boltface is like putting metal rod centered the boltface and a live center on the tailstock. The boltface holds the cartridge centered in contrast to the claw extractor letting the cartridge drop in the bottom on the chamber. The pressure on the bullet nose aligns it in the bore. Keep good records of temperature, alloy and casting temperature to see how the bullet fits.

Spitzers?  I kind of made a big deal about where the gas check sits in the case because I think it’s important. – I do too. Empirical research to this date, but I have a 7mm BR and a 7mm-08 I want to do a structured study on. The SAECO 160 grain mold and the RCBS 168 grain mold together.

But what I think and what someone with 20 years of cast accuracy knows is two different things. – I am never sure what I know, I am restructuring my testing methodology in this coming 7mm endeavor. When you think you have the right answer, go back to see if you have the right question.

Farm boy from Illinois, living in the magical Pacific Northwest

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Wm Cook posted this 13 May 2022

Attached is a 25 shot group. It shows that the sight is 1/8th low and 1/4" left. That is not observable with 5 shot groups.

Ric you're right on that. And nice group.  I'm pretty naive so I just assumed that not many folk took 5 shot groups as the end all for cast load development.  About "true zero"; knowing where the center of the group is will keep you from going crazy in Score matches and 25 shots will show the fliers.  That'll keep you from jumping off a cliff and start you spinning on the scope turrets when one shot doesn't go where you though it would.  

About fliers: I think the article John Anderson wrote in the last FS was the definitive work on culling away brass as the culprit for fliers.  Assuming the shooter has immunity from making mistakes that leaves either the powder, mold and/or inadequate load development as the problem.

The first step is research; checking the Fouling Shot equipment listing for rifle and caliber as a reference.

Bud I would agree with that as far as the mold choice but even that would require hands on tinkering in the shop to finalize the fit to bore.  The bore rider is the simplest design (IMHO) and even that has to be fitted to the bore either with beagling or choice of alloy.  But match reports are a great place to start for mold selection. Powder selection is great topic and I'll start a thread specific to powder using your post if you don't mind.  BTW did you mean N135 or N335 in your post?

As a disclaimer, there are many others that shoot for accuracy that do not compete.  I fully respect their knowledge and skill.  But match reports are the only source those that do not decades of individual experience in cast accuracy.  And if its shot and measured in a registered match its solid information (cast competitors don't lie about their equipment list like those jacketed BR shooters).

At this point in my learning curve I respectably disagree with you about seating depth.  I qualify that comment by saying that although I've cast for almost 30 years its only been in the past year that I tried to keep them all going through the same hole.  Let me put it to you this way; I think seating depth is to jacketed accuracy as bullet fit is to cast.  And right behind bullet fit to throat for cast accuracy I would put powder choice.  And for clarification could you explain "witness mark at .050".  I came from a jacketed accuracy world where the key words were kissing and jam.  And then we speak about thousands of an inch off of jam. 

So with only one powder and one mold where do you start your seating depth for bore riders?  Spitzers?  I kind of made a big deal about where the gas check sits in the case because I think its important. But what I think and what someone with 20 years of cast accuracy knows is two different things.  Thanks, Bill.

 

 

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joeb33050 posted this 13 May 2022

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joeb33050 posted this 13 May 2022

Joe sez: "Nope. Zero the rifle 1.234" low, 2.345" right., or anywhere, the stdev of measures is independent of POI/POA. 

==============

Joe, now my BS detector has rung so hard that the bell is broken and fallen on the floor.  Maybe I should think about it some more before answering.

 

How about this. Set sights to hit anywhere. Fire 25 ex shots at 25 bullseyes. Measure x and y of each shot.  This is the data, all there is.

There are 12 2-shot groups, shots 1-2, 3-4, 5-6, 7-8...etc.

Put the x,y coordinates of shots 1 and 2 on a piece of graph paper and measure 2-shot group size. 

there are 5 5-shot groups. put the x,y coordinates of shots 1-5 on a piece of graph paper and measure 5-shot group size.

Or, calc stdev of x and y.

Calculate whatever you wish, the 25 x,y pairs are all the info there is.

The precision of each shot is in the location of the bullet hole, ALL the information in a shot is in the xy coordinates of the hole. There is no other information. We can calc 2-shot or 5-shot or 7- shot group sizes, or whatever, we can argue  about mean radius, but we're ALWAYS dealing with bullet hole location.

I spent half an hour and made an EXCEL worksheet that calculates 2, 3, 4, and 5 shot group size from xy coordinates.The computer calculates it all, makes calcs easy.

The x,y coordinates of the bullet hole are ALL the info in the shot; and 1 shot per bullseye is the "best" way to get and see that info.

joe b.    

 

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