How much "Extreme Spread" is acceptable in competition?

[Brians356]

So far you have made 2 claims -- that Mulligan's dataset is too small to draw conclusions, and that primer weight matters.

To be fair to Evan, he didn't exactly say too small to draw conclusions (in fact he reached the same broad conclusion), he said "The data set is too small to have any sort of valuable signal to noise analysis applied or quantification of error." Your request for a T-test suggests you disagree with that more specific claim as well. Just trying to keep it real, it's a worthwhile discussion!
-

 

[Evan]

That's the first data set, presented as a scatter plot. Error bars on the average represent 2SD either way, capturing 95% IF it is gaussian. That's a difficult data set to make statistical predictions from. The overlap in error is huge. 1SD, 10fps, is a weight change of 0.04 gns or ~30% of full scale.

 

[Toby Bradshaw]

View attachment 1070847
That's the first data set, presented as a scatter plot. Error bars on the average represent 2SD either way, capturing 95% IF it is gaussian. That's a difficult data set to make statistical predictions from. The overlap in error is huge. 1SD, 10fps, is a weight change of 0.04 gns or ~30% of full scale.

You don't (or at least shouldn't) use regression analysis for categorical variables, so why plot it that way?

And you didn't plot the most recent dataset. Why not? Is it because the means are 2-3 standard deviations apart (which is why the t-test is significant at p~0.01)?

 

[Evan]

Nevermind...

 

[6MMsteve]

Black Art

 

[Mulligan]

Pondering,
One thing (besides primer weight making a difference) that really stands out in this test, is the velocity difference between the two pieces of brass. I noticed the average velocity of brass #1 was exactly 25 fps slower than the average velocity of brass #2 in both the light and heavy primer tests. I consider this to be significant in the quest for better (smaller) extreme spreads in my hand loads.

I plan to spend some time evaluating the two pieces of brass and doing another test based on what I find (likely nothing new to the long range crowd).

Question,
What methods of sorting brass has proved to be most beneficial as it relates to reducing extreme spread?

1) Volume Sorting using;
A) H20
B) Ball powder
2) Vertical on target
3) velocity on chron
4) Case weight
5) ?????

I assume I should use;
1)brass that has been fire-formed to the chamber?
2)brass that has been uniformed externally?
3) what else???

I know ES is not the holy grail of long range accuracy, however having an ES of over 20 fps based on brass alone cannot help.
I will use this information to frame up the next test.
Thanks again
CW

 

[Dusty Stevens]

Id like to see the weight on those pieces of brass

 

[Mulligan]

Id like to see the weight on those pieces of brass

Just shuffled down to the loading room and turned on the scale, no warm up at all.
The FX-120i says
#1 107.32 grains
#2 107.30 grains
CW

 

[Dusty Stevens]

Just shuffled down to the loading room and turned on the scale, no warm up at all.
The FX-120i says
#1 107.32 grains
#2 107.30 grains
CW

Man thats awful close to be giving an exact spread like that

 

[Mulligan]

Man thats awful close to be giving an exact spread like that

Well, it might be just a fluke?????
That is why I plan to test it.
Maybe, just maybe, case weight has no correlation at all to case volume?
CW

 

[dkhunt14]

Well, it might be just a fluke?????
That is why I plan to test it.
Maybe, just maybe, case weight has no correlation at all to case volume?
CW

It can be other things. Maybe harder or softer, giving more neck tension. Maybe thicker or thinner in neck. Lots of things can change it. Be interesting to see the H2o capacity. Matt

 

[dkhunt14]

A s a side note, some of my best loads for 1000 yard BR have been in the 12 to 20 ES range. Some of my worst vertically have been in the 2 to 3 ES range. I believe it's still mostly about tune for the barrel. Matt

 

[Mulligan]

It can be other things. Maybe harder or softer, giving more neck tension. Maybe thicker or thinner in neck. Lots of things can change it. Be interesting to see the H2o capacity. Matt

I will check it in a bit
CW

 

[Mulligan]

It can be other things. Maybe harder or softer, giving more neck tension. Maybe thicker or thinner in neck. Lots of things can change it. Be interesting to see the H2o capacity. Matt

#1 without primer was 107.32, with a used primer installed and filled with H2O it weighed 144.44. H2O weight= 37.12

#2 without primer was 107.30, with a used primer installed and filled with H2O it weighed 144.38. H2O weight= 37.08

I didn’t weigh the spent primers prior to installation, I have no idea how much that effected this.

Appear pretty darn close to me. Like separating fly s#!t from pepper.

CW

Edit
The scale was not warmed up during either of these weights so quality is suspect.
CW

 

[_Raining]

A s a side note, some of my best loads for 1000 yard BR have been in the 12 to 20 ES range. Some of my worst vertically have been in the 2 to 3 ES range. I believe it's still mostly about tune for the barrel. Matt

Let's say 42.1 grains has a ES of 3 but your 42.7 load has an ES of 20 but shoots better at distance. This test doesn't dispute that, the test raises the question of; If you weighed your primers could you get the ES of the 42.7 grain load down and make even better vertical. There was also a side effect of this test which showed that one case produced velocities different from the other consistently, and the value for the difference between cases is on par with the value of the difference between heavy and light primers so they both seem to have equal impact. One question is, how low could you get that 20 ES if you weight sorted primers and had brass that was "velocity sorted", and then the next question is does reducing the ES of that load make a difference on target and if it does, is that difference worth the effort.

 

[dkhunt14]

Its possible I guess, that if you got that good load down in ES, it would help some more. I tried playing with that load of 20 ES and it never got much better numbers or shot better groups. That load of 20ES shot a world record 6 match group aggregate in heavy gun. It was 2005 and the very first sub 6 inch aggregate ever fired. It was a 308 Baer shooting 240 Sierras. The vertical was no worse then the wind. They were fairly round groups. I do sort everything except case volume. I am pretty anal about all measurements of bullets and cases. Matt

 

[Mulligan]

@Mulligan

Where's the target picture?

Tom

You’re killing me Smalls!!
CW

 

[seymour fish]

View attachment 1071225

Pondering,
One thing (besides primer weight making a difference) that really stands out in this test, is the velocity difference between the two pieces of brass. I noticed the average velocity of brass #1 was exactly 25 fps slower than the average velocity of brass #2 in both the light and heavy primer tests. I consider this to be significant in the quest for better (smaller) extreme spreads in my hand loads.

I plan to spend some time evaluating the two pieces of brass and doing another test based on what I find (likely nothing new to the long range crowd).

Question,
What methods of sorting brass has proved to be most beneficial as it relates to reducing extreme spread?

1) Volume Sorting using;
A) H20
B) Ball powder
2) Vertical on target
3) velocity on chron
4) Case weight
5) ?????

I assume I should use;
1)brass that has been fire-formed to the chamber?
2)brass that has been uniformed externally?
3) what else???

I know ES is not the holy grail of long range accuracy, however having an ES of over 20 fps based on brass alone cannot help.
I will use this information to frame up the next test.
Thanks again
CW

Go with A).

 

[seymour fish]

Go with A).

Flash holes identical?

 

[rardoin]

Let's say 42.1 grains has a ES of 3 but your 42.7 load has an ES of 20 but shoots better at distance. This test doesn't dispute that, the test raises the question of; If you weighed your primers could you get the ES of the 42.7 grain load down and make even better vertical. There was also a side effect of this test which showed that one case produced velocities different from the other consistently, and the value for the difference between cases is on par with the value of the difference between heavy and light primers so they both seem to have equal impact. One question is, how low could you get that 20 ES if you weight sorted primers and had brass that was "velocity sorted", and then the next question is does reducing the ES of that load make a difference on target and if it does, is that difference worth the effort.

I have weighed primers and I have not seen any significant improvement in ES. I, like Matt also tune by the groups, not by numbers; more often than not my best groups at distance are not the lowest ES groups.