Analyze My Groups

[solarshooter]

I wouldn't go that far.

I said what I said!

Seriously though, can you show me a statistically robust test that shows that changes in powder charge or seating depth have an effect on precision? I have tested it several times and found the conclusion to be they do not. And of course there's the tests Litz ran and thoroughly documented in his books. And many many examples on this forum.

 

[Castle Rock]

I said what I said!

Seriously though, can you show me a statistically robust test that shows that changes in powder charge or seating depth have an effect on precision? I have tested it several times and found the conclusion to be they do not. And of course there's the tests Litz ran and thoroughly documented in his books. And many many examples on this forum.

No one is interested in changing your mind, you are welcome to your beliefs.

 

[solarshooter]

No one is interested in changing your mind, you are welcome to your beliefs.

They're not just beliefs... that's my point.

 

[Gstew1930]

I said what I said!

Seriously though, can you show me a statistically robust test that shows that changes in powder charge or seating depth have an effect on precision? I have tested it several times and found the conclusion to be they do not. And of course there's the tests Litz ran and thoroughly documented in his books. And many many examples on this forum.

I started doing the same thing. If the load doesnt shoot i move on. Usually a powder change will get me what im looking for

 

[stan_wa]

I support the claim: "Small changes in seating depth and powder charge will not have a measurable effect on precision"

I've tried to make powder charge or seating depth make a difference, and honestly, it just doesn't. Let me provide a good example. I would challenge anyone to show the statistical significance of changing 0.2 grains in powder or .020" in seating depth. How would you do this, you ask?

To keep it simple:

• Pick your favorite load and shoot 30 rounds at one bullseye
• Load 30 rounds at your favorite load +0.2 grains and shoot at another bullseye
• Load 30 rounds at your favorite load with +0.02" CBTO and shoot at a third bullseye

Then you'll see they don't look that different. If you're still not convinced and need more concrete proof, you can do things the hard way: shoot small enough groups to see each hole, plot XY coordinates of each shot, virtually overlay them to 1 group per load, and calculate the mean radius of each shot. Run a t-test on the values of mean radius for each group.

If 30 rounds is too much for you, 20 might be enough for good gun ( .3 MR or less), but 10 or less is just a waste of time.

I recently tried changing my 6mm load from 40 to 42 grains (a huge change) and shot 20 rounds of both. The group size/mean radius were .75"/.21" and .95"/.28". You might think, "Wow, look, it made a difference!" Well, first off, those are tiny differences driven by just 1 or 2 shots most off center. So I'm arguing this is pure noise.

You may say "I don't know about that..." So I went full nerd and plotted X/Y values for each point and ran a t-test on the groups. The results were:

t-statistic: -1.151
p-value: 0.265

If you don't speak statistics (I barely passed stats myself...), here's what these results mean: per the chat bot

These statistics indicate the results are not statistically significant. The p-value of 0.265 is greater than the conventional significance level (0.05), meaning there is insufficient evidence to reject the null hypothesis. The observed difference could reasonably be attributed to random chance, and the data does not support finding a meaningful effect or difference between the groups being compared.

My absolute favorite response to this is, "I'm not gonna waste 90 rounds running some test." To which I say: "Ah, but you'll waste far more than that chasing numerous combinations of powder charge and seating depth to produce a difference that isn't measurably different. And even if you could get a measurable difference, that difference still won't meaningfully impact your odds of hitting your target!"

 

[Schmo]

Yeah, I stopped doing seating depth and powder charge adjustments. I pick .035” off the lands, and find pressure then back off a grain or so. Shoot for groups. I only swap powder and/or bullet.

 

[stan_wa]

OP
regarding the group. my advise, shoot a big group from the absolute best most stable possition you can. like so stable that when you dry fire the crosshairs moves less than .25 moa. For me prone with front and rear bag. this will give you a good idea of what you load/ rifle can do.

This will give you a baseline, now when you shoot any less good position. you can compare back to that to know is it me or is it just the best my load/rifle will do.

For a average gun those are ok groups. I have seen some guns that wont shoot any better than that. Till you know what the gun does, its very hard to know what you can do.

Then shoot larger groups and measure Mean radius to start to see if those positions really made a difference. in general .1-.2 MOA in mean radius is amazing. .3-.4 is pretty dang good .4-.5 is ok .5 is about the worst i would want in hunting gun unless i was limiting my range

 

[mainbeam pursuit2]

I agree with a lot of what has been said above. Everyone has limits to what they want or expect. I suggested the Cortina video if you want to go that far down the rabbit hole. Myself, I went down that hole for a while. I felt I was wasting my time and components trying to improve on something that was already working. I couldn't find enough changes to stick with it. Not sure I can shoot well enough to see the minor differences, if any over the long haul.

 

[Schmo]

I know I’m capable of 10 shot, sub MOA groups, when I’m executing perfectly. I’ve done it with my .223.

 

[Jordan Smith]

I said what I said!

Seriously though, can you show me a statistically robust test that shows that changes in powder charge or seating depth have an effect on precision? I have tested it several times and found the conclusion to be they do not. And of course there's the tests Litz ran and thoroughly documented in his books. And many many examples on this forum.

I'm a physicist. I take the word "prove" very seriously. That word is avoided in science. There may be data or a body of evidence that supports a certain hypothesis or conclusion, but empirical "proof" is essentially impossible.

I've read Litz' books and don't recall him coming to that conclusion. The Hornady guys more or less came to that conclusion, though.

Accumulating the statistically meaningful sample size needed for such a certain conclusion in answering such a complex multivariate question is practically infeasible. The less variation in a given population, the more statistical power achieved with a smaller sample size, and we see that SRBR shooters certainly believe that powder charge and seating depth matters in optimizing precision. Whether or not that level of resolution matters for you and your application, however, is a separate question.

 

[solarshooter]

I'm a physicist. I take the word "prove" very seriously. That word is avoided in science. There may be data or a body of evidence that supports a certain hypothesis or conclusion, but empirical "proof" is essentially impossible.

I've read Litz' books and don't recall him coming to that conclusion. The Hornady guys more or less came to that conclusion, though.

Accumulating the statistically meaningful sample size needed for such a certain conclusion in answering such a complex multivariate question is practically infeasible. The less variation in a given population, the more statistical power achieved with a smaller sample size, and we see that SRBR shooters certainly believe that powder charge and seating depth matters in optimizing precision. Whether or not that level of resolution matters for you and your application, however, is a separate question.

My theory is the simpler one. Yours is the complex, unproven one. Any actual test I've seen, even if not perfect enough for a physicist, has shown the complex hypothesis on tuning ammo with these small tweaks to be untrue. And your counter argument is based on what some "SRBR shooters certainly believe". Sorry but that's a really flawed set of reasoning.

 

[BBob]

Any actual test I've seen

So you’ve never actually taken a good true BR gun (long or short) and put it through its paces? As far as common guns in the hands of common people I’d agree most won’t see seating depth or powder charge changes. Either one or both are incapable of it.

 

[Macintosh]

Whether or not that level of resolution matters for you and your application, however, is a separate question.

When talking about a hunting rifle, field positions, and practical application rather than competition high-precision application and equipment, this quote right here seems highly relevant. I don’t know enough to argue one way or another if seating depth or small variations in powder charge have any effect on precision. However, it seems very plausible to me that if they do, the effects could easily be lost (ie unmeasureable) in the noise of the other variables that are inherent in field shooting. Just for example look at the WEZ very small improvements in hit-rate resulting from increasing precision. Which might render their effect “not worth bothering to think about” given this application.

 

[solarshooter]

So you’ve never actually taken a good true BR gun (long or short) and put it through its paces? As far as common guns in the hands of common people I’d agree most won’t see seating depth or powder charge changes. Either one or both are incapable of it.

On the contrary, I've done exactly that:

Post in thread 'Your Groups Are Too Small'

Jan 21, 2024

Bet you $100 that if you shot a 30 round group of at 54.5, 55.0, 55.5gr- there is functional difference, and almost certainly they will be within statistical variability- you have “engineered” yourself into believing that you can control small variables to effect a real outcome.

I'm assuming you meant NO functional difference. True. I guess I would need to do that to prove that the selection method is valid or not. Like I said earlier, I have already proven this for a different powder combo, but it's not certain for this powder. I could pick the worst charge from the initial...

• solarshooter

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[stan_wa]

I can say that I have tested it a bunch of times not just the one mentioned here I would say at least four different guns with 10 different loads and have never seen substantial changes. When measured with real data not just group size on small groups.

I think it’s much easier to say that most of what people believe “are differences “ , regardless of how good they are at the craft is tied to a fundamental misunderstanding in natural variance of sample size.

Whether or not that level of resolution matters for you and your application, however, is a separate question.

Considering its Rokslide and talking about hunting, I think we could boil this down to a pretty simple metric .

What do you think about , if you can’t increase your percentage via ( Wes) by 10% or more you won’t even notice the difference on your hunt ?


I want to add that what we are arguing for will make your life easier and even though I’m pretty sure that I’m correct . the reason that I even care to debate it with you is that I legitimately think it’ll simplify and make your entire process more effective and better. I don’t really care about being right. I just want to save you the headache . because two years ago I was at the exact same persuasion as you And wasting a bunch of time.

 

[BBob]

On the contrary, I've done exactly that:

Cool, after reading that I have thoughts but…. carry on your campaign

 

[huntnful]

When talking about a hunting rifle, field positions, and practical application rather than competition high-precision application and equipment, this quote right here seems highly relevant. I don’t know enough to argue one way or another if seating depth or small variations in powder charge have any effect on precision. However, it seems very plausible to me that if they do, the effects could easily be lost (ie unmeasureable) in the noise of the other variables that are inherent in field shooting. Which might render their effect “not worth bothering to think about” given this application.

I believe this is spot on. Or basically any application that has to do with killing animals. I don’t think there will ever be a circumstance where a .005 seating depth change, or a .5gr powder window would result in killing, or not killing animal.

Shooting the smallest groups in the world though….. IDK, ask the guys that shoot the smallest groups in the world. Apparently they all think it matters. Even though none of them have posted a 1000 round test for us to analyze. I’m going to believe them, because they actually do it, live it, and spend all their money and time on it…. not just read about what others have done.

For me? .010 off and 1gr. under pressure. If it don’t shoot, I’m moving on lol.

 

[solarshooter]

Cool, after reading that I have thoughts but…. carry on your campaign

Please share them!

 

[stan_wa]

I know I’m capable of 10 shot, sub MOA groups, when I’m executing perfectly. I’ve done it with my .223.

I have often been surprised by how much a difference the gun makes
. more so than the shooter, when it comes to shooting prone on a bench with a good set up. if me and three buddies sit on the bench, shoot groups and switch guns the group size follows the gun not the shooter. We are not competition bench shooters just diligent shooters. This convinced me thoroughly that with a stable position you can fairly accurately measure the precision of the gun and the human error portion is can be very small.

This is why I say I think the best first step is to characterize the performance of your gun so then from there you can know when you change position it’s you and not the gun

 

[solarshooter]

Shooting the smallest groups in the world though….. IDK, ask the guys that shoot the smallest groups in the world. Apparently they all think it matters. Even though none of them have posted a 1000 round test for us to analyze.

The thing is, they think it matters because they do small sample ladder testing because they don't want to shoot a 1000rd test. But I guarantee you they burn way more than 1000rds chasing nodes. And they shoot the smallest groups in the world because they use the absolute best components, make the absolute most insanely consistent ammo, and shoot light recoiling cartridges out of heavy guns. It's not a mystery.