Statistics

[INTJ]

Maybe you could share that insight for probably the 100th time. For those of us who has no clue or are late to the party

It's just the colored bullet tip, round robin tuning "ladder" we shoot to evaluate powder, seating depth, bullets, primers, neck tension, what ever.

I load up 17 rounds. Five are to ensure I am centered at 1000 yds. Then I shoot four three shots groups, all at the same time to the same POI. I shoot one round from load one, then one from load two, then one from load three, then one from load four; then repeat. The bullet tips are colored so I can connect the dots and see where each group printed.

That is the basic method. The more refined one gets with powder charges and seating depths, the better the groups--usually.

 

[762plinker]

It's just the colored bullet tip, round robin tuning "ladder" we shoot to evaluate powder, seating depth, bullets, primers, neck tension, what ever.

I load up 17 rounds. Five are to ensure I am centered at 1000 yds. Then I shoot four three shots groups, all at the same time to the same POI. I shoot one round from load one, then one from load two, then one from load three, then one from load four; then repeat. The bullet tips are colored so I can connect the dots and see where each group printed.

That is the basic method. The more refined one gets with powder charges and seating depths, the better the groups--usually.

define the conditions when this is a valid test ??
and why not just shoot 4 three shot groups vs a 12 shot string

 

[dcali]

I would say that it's its a mistake to equate "statistical relevance" to "lots of data". We want the *highest* statistical relevance with the *lowest* amount of data. Unfortunately, those factors are at odds with each other.

Practically, what we are trying to avoid is knowing things that just aren't true. There is more than one way to do that. One is to collect a lot of data -CAREFULLY. Carefully, because data lies to us. Another is to rely on data that others have collected. This is how the entire engineering profession works, and their results speak for themselves. It's also how short range benchrest shooters have arrived at PPCs, and the bullets, twists, barrels, stocks, etc they use. The don't have to collect the data because countless others have done it for them.

But word of mouth anecdotal data is very unreliable and inefficient. It's slow to be communicated and often poorly collected/bad. But in aggregate, it works. Collecting and communicataing (via the internet, for example) GOOD, relevant data helps us all.

There is a danger in "cargo culting" (a software idiom for doing something because everyone else is doing it without understanding why). That's true for math and for aping the latest shooting trend. Both will tend to lure you to comfortable but incorrect conclusions.

Edit: A perfect example. Many experienced shooters believe in velocity "flat spots" being a way to tune a load. This is bunk, and you can figure this out one of three ways:

- you can listen to people who've played around with this idea and discovered that it's just not reliable or helpful. You rely on their experience.

- you can just shoot a bunch of rounds to see if it's actually true and repeatable. This requires a reasonable amount of data, but it will tell you the answer. But 50 rounds and an afternoon trip to the range will tell you without a doubt that flat spots do not even exist, let alone point you in the direction of a good load.

- you can just keep bumbling along thinking it's true and being the blind squirrel now and then until you figure out better ways. You may never even realize you were wrong.

The first is the easiest if you listen to the right people (easier said than done). The second is a trap if you don't at least have some grasp of statistics. A good grasp of statistics will make the 2nd option a lot faster and easier. The third is what most guys seem to do.

Don't be afraid of the math, just understand it's limits, when to apply it, and what it actually tells you. Good servant, poor master.

 

[tom]

define the conditions when this is a valid test ??
and why not just shoot 4 three shot groups vs a 12 shot string

Thanks for tagging Mr Blaine, this ought to be a shit show! Lol

Mike, your question is actually quite valuable to the thread. So what you ask, answers itself is what I would say. Sometimes I run groups, but still all 12 at once. I really only round Robin when roughing in, or extremely fine tuning trying to decide between 2 "loads" that are extremely close in statistics to date. By comparing in this way, you are equalizing the conditions, good or bad you still see a winner and direction to proceed. When you're getting close, these 3 shot groups start to become 6 or even 9 shot groups as the increments become finer, which helps the confidence in the results as well. Yes, I've seen the occasional barrel not hold up for 5 or 10 shots, but the odds are against it from everything I've seen. Usually in those cases, those barrels never were capable in todays world.

Tom

 

[Jdne5b]

Scientists need statistics and statistical significance.

As a competitive shooter, I just need confidence that my load is good, and repeatable.

 

[INTJ]

define the conditions when this is a valid test ??
and why not just shoot 4 three shot groups vs a 12 shot string

It is valid in most conditions.

Shooting all shots at the same time to the same POI greatly mitigates those micro conditions that can cause one group to be smaller than another. When you shoot groups, each one is shot in a slightly different condition. When you shoot them all at the same time, it evens that out. So when you get two overlapping 3-shot groups where the combined vertical is under say 3-4" or better at 1000 yds, you have found a repeatable load. When you find a 1" 3-shot group shout round robin style, you know it wasn't just the wind "blowing them in."

All that said, try it if you want. Don't try it if you don't want--it doesn't matter to me. Each person has to find their own way.

 

[CharlieNC]

Maybe its not apparent but shooting a ladder (esp round robin style) and judging the results based on a stable point of impact to identify a node is a very statistically valid method. Judging the same ladder based only on group size, which is much more variable, not so much. This is one of those "experience pays" perspectives that often shows up here.

 

[Northridge]

Thanks for tagging Mr Blaine, this ought to be a shit show! Lol

Mike, your question is actually quite valuable to the thread. So what you ask, answers itself is what I would say. Sometimes I run groups, but still all 12 at once. I really only round Robin when roughing in, or extremely fine tuning trying to decide between 2 "loads" that are extremely close in statistics to date. By comparing in this way, you are equalizing the conditions, good or bad you still see a winner and direction to proceed. When you're getting close, these 3 shot groups start to become 6 or even 9 shot groups as the increments become finer, which helps the confidence in the results as well. Yes, I've seen the occasional barrel not hold up for 5 or 10 shots, but the odds are against it from everything I've seen. Usually in those cases, those barrels never were capable in todays world.

Tom

The good news is I only have to convince myself as to what I gather from a given ladder or not regardless of “depth” of data collected… what seems to get missed as Alex makes his point is the assumption over Short “time” with a fresh situation or barrel that it won’t support 100’s of ladders from previous ventures to a common result or trend.. the personal Data collection for guys like Glenn Kulzer Tom Mousel Alex wheeler or my Shawn Williams and many other Competitors in Long range bench rest actually is very “Deep” regardless the depth of collection a guy has to eventually pick a path that may or may not compete but eventually guys need to leave the comfort of there couch and Fuxx up some targets Lol all in good fun

Shawn Williams

 

[JEFFPPC]

I want to stir the pot a little on this discussion. To ad another point of view to the discussion around statistics. Lately theres been a lot of talk about what is statistically relevant when it comes to testing things or tuning a rifle. Most of the stuff I have seen comes from people with a scientific background. I wanted to ad a point of view from a background of building rifles that have to win matches and shoot the smallest aggs possible.
In my opinion, we want to tune a barrel in the least statistically relevant way possible SO LONG as it produces results. If I could tune a barrel in 5 shots and go break a record and win matches consistently with that method it would be the best tuning method there is. But also the least likely to stand up to scientific scrutiny.
The reality is that none of my tuning methods, or any of the methods used by my customers to win or break records would be considered statistically relevant. It blows my mind when I read some of this stuff. We have to test powders, primers, neck tension, seating depth, tuner test, ext. There are ways to do this with only a small sampling. When I am starting with a new rifle and I want to try 3 or 4 different powders, it only takes about 10 shots to know if that barrel likes that powder or not. Same goes for primers. Group size is another thing. 3-5 shot groups are not relevant? I dont have enough fingers and toes to count the records that say they are. What are we trying to do? Tune a rifle or create data?
What I am trying to stop is the guy that calls and says he is struggling to tune his rifle, hes shot a ton of groups. Piled up plenty of statistically relevant data, but has only tried one powder, one bullet, and one primer, and now has his barrel 1/3 shot out because he would not make decisions based on a small sampling.

Alex, best post you have ever written. A lot of guys own expensive good guns. A very tiny few are " shooters". There are many more barrels worn out searching for a load then are worn out being competitive on the line. Our woke experts teach more is better, complicated even more impressive but a simple process is beyond them.

 

[762plinker]

i think i need to point out that tom can shoot 'QUICKLY"....so i think part of this process requires quick smart shooting. that means a rifle has to be setup so it does not move out of alignment and follow up shots can be done with minimum fuss

 

[Dimner]

.

Then I starting tuning the way Alex (and @tom and @GlennK and a bunch of others) tune. My groups shrank and I put a lot less rounds though my barrels.

Is there a thread with a writeup of this method? I'd love to learn it and/or see how far off I am of using it currently.

I should have finished the thread first

 

[Bob3700]

I want to stir the pot a little on this discussion. To ad another point of view to the discussion around statistics. Lately theres been a lot of talk about what is statistically relevant when it comes to testing things or tuning a rifle. Most of the stuff I have seen comes from people with a scientific background. I wanted to ad a point of view from a background of building rifles that have to win matches and shoot the smallest aggs possible.
In my opinion, we want to tune a barrel in the least statistically relevant way possible SO LONG as it produces results. If I could tune a barrel in 5 shots and go break a record and win matches consistently with that method it would be the best tuning method there is. But also the least likely to stand up to scientific scrutiny.
The reality is that none of my tuning methods, or any of the methods used by my customers to win or break records would be considered statistically relevant. It blows my mind when I read some of this stuff. We have to test powders, primers, neck tension, seating depth, tuner test, ext. There are ways to do this with only a small sampling. When I am starting with a new rifle and I want to try 3 or 4 different powders, it only takes about 10 shots to know if that barrel likes that powder or not. Same goes for primers. Group size is another thing. 3-5 shot groups are not relevant? I dont have enough fingers and toes to count the records that say they are. What are we trying to do? Tune a rifle or create data?
What I am trying to stop is the guy that calls and says he is struggling to tune his rifle, hes shot a ton of groups. Piled up plenty of statistically relevant data, but has only tried one powder, one bullet, and one primer, and now has his barrel 1/3 shot out because he would not make decisions based on a small sampling.

Alex,
There is no doubt what u say about keeping a short range benchrest rife in tune is true. None of our gun games focus on getting an “A” in our statics lab project. Adjusting ur loads or tuner to shoot the smallest groups at 100/200 yds. is the focus. I am sure that u can get ur rifle tune to 97% accuracy fairly fast. The challenge is then to keep it there when conditions change that open ur groups .050”.
Different disciplines require different techniques.
Shooting off bags n rests or bipods n bags is a whole different game than MR/LR prone with iron sights n a sling. I have had one load for my 6mm BRX or 308 Palma rifle that will shoot high X counts in any of the bbls I have put it in. If a new bbl won’t shoot that load, I look for a different bbl. The amount of atmosphere between the rifle n the target far out ways any effect that .005” difference in bullet seating depth has.
I feel u are correct in the fact that with experience we can zero in relatively quickly on what is going to shoot in a given rifle. The issue is that many who post here don’t have that level of experience and then someone with a math major/minor comments on the validity of a testing method. They know the science but may be a bit short on shooting/ loading experience. So a shooter may be led to believe they need a statically valid sample size of groups to confirm their loads. Like u , I don’t want to use a ton of components n bbl life searching for a unicorn load/ group.
Our competition group just completed some 600 yd testing on three different rifles. Bullets were tested in a return-to-battery rest with powders known to work in that cartridge. Testing showed within 10 shots if that bbl was going to shoot that bullet well.
Guess it depends on the goal. Are u focused on testing or competing. I thing as a competitor, u don’t want to get caught up in “ Analysis Paralysis”.

 

[Keith Glasscock]

Alex, you hit the nail on the head, again!

I'll say it again: It is impossible to find the "best" load for a barrel during its life through a testing process. There is too much random noise involved.

Instead, one is looking for a load that performs to the needs or expectations. There might be a few powders, a couple of primers, several bullets and whatnot that meet that requirement for a given barrel. Another barrel can be picky, and will suggest strongly that it isn't happy with a particular component. That is where experience comes in.

Back to the topic at hand, statistic significance. For me, statistical significance is used to answer large questions like "does adding a heavy suppressor to the end of a barrel change group size" or "Does seating primers with XYZ tool change the SD?" Neither of which are appropriate to test with your best match barrel. That's what the mediocre barrels are for!

IMO, science and match shooting are separate, but complimentary. If someone wins a match or two with a certain combination of factors, it could be fodder for a scientific test (statistically significant stuff). If the science (properly done) tells us that a certain combination reduces group sizes or velocity variation, then match shooters can take that up and try it out to see if it is a good fit for their context.

That is why it is so important to present information about testing dispassionately and without the bandwagon fallacy that we see so often. Just because it won on Sunday, doesn't mean you should buy one on Monday...

 

[BoydAllen]

Alex,
There is no doubt what u say about keeping a short range benchrest rife in tune is true. None of our gun games focus on getting an “A” in our statics lab project. Adjusting ur loads or tuner to shoot the smallest groups at 100/200 yds. is the focus. I am sure that u can get ur rifle tune to 97% accuracy fairly fast. The challenge is then to keep it there when conditions change that open ur groups .050”.
Different disciplines require different techniques.
Shooting off bags n rests or bipods n bags is a whole different game than MR/LR prone with iron sights n a sling. I have had one load for my 6mm BRX or 308 Palma rifle that will shoot high X counts in any of the bbls I have put it in. If a new bbl won’t shoot that load, I look for a different bbl. The amount of atmosphere between the rifle n the target far out ways any effect that .005” difference in bullet seating depth has.
I feel u are correct in the fact that with experience we can zero in relatively quickly on what is going to shoot in a given rifle. The issue is that many who post here don’t have that level of experience and then someone with a math major/minor comments on the validity of a testing method. They know the science but may be a bit short on shooting/ loading experience. So a shooter may be led to believe they need a statically valid sample size of groups to confirm their loads. Like u , I don’t want to use a ton of components n bbl life searching for a unicorn load/ group.
Our competition group just completed some 600 yd testing on three different rifles. Bullets were tested in a return-to-battery rest with powders known to work in that cartridge. Testing showed within 10 shots if that bbl was going to shoot that bullet well.
Guess it depends on the goal. Are u focused on testing or competing. I thing as a competitor, u don’t want to get caught up in “ Analysis Paralysis”.

Alex's sport is 1,000 yd, benchrest.

 

[M-61]

Statistics is a tool, but it is often not the right tool for the job because we do not have the luxury of unlimited time, materials, or budgets, and lacking tunnels, most of us do not have the luxury of living where good test conditions are frequent.

100% agree
A run on sentence that incorporates at least 6 facts that are “true reality “.
From the right tool to the time you’ve covered it all.

 

[BoydAllen]

100% agree
A run on sentence that incorporates at least 6 facts that are “true reality “.
From the right tool to the time you’ve covered it all.

Yes it is. Thanks. Obviously, sometimes I forget to reread a post before posting it.

 

[jackieschmidt]

I know Alex is more in to the Long Range Disciplines, but there are a lot of us short range group and score shooters that adhere to one dimension in our programs.

That is, we basically shoot the same combination all of the time.

I have not shot anything but Kreiger and Bartlien barrels for the past 20+ years. I shoot the same powder. The same bullet. And 95% of the time, the same load, neck tension, and seating depth In both my 6PPC and 30 BR.

If a barrel will not shoot these combos, it’s coming off. Components and range time are far too valuable to waste on barrels that I have no confidence in.

The only time I take a side road is for a specialty event such as the TackDriver. My little 68 grn FB is a little weak out at 300 meters, a fellow shooter, and custom bullet maker, has sent me some of his 68 grn double ogive boat tails to try. If they show promise, I will use them after working up a tune.

 

[Dave Way]

Numbers lie. Targets don’t.

 

[Bill Norris]

Numbers lie. Targets don’t.

I second that.

 

[M-61]

Yes it is. Thanks. Obviously, sometimes I forget to reread a post before posting it.

Meant as a backhanded compliment, not a criticism of structure, but a compliment on content.