Es and Sd troubleshooting flow chart

[AJC]

Is there a standard process or maybe even a flowchart for resolving problems with beyond desirable numbers. Been doing a bunch of reading and I have yet to run into something that would walk someone through a standard process. Most likely the most experienced guys just "know what to do". May make a decent article or project for someone during the winter.

 

[Bart B.]

What problems need solved?

 

[AJC]

What problems need solved?

I dont have an issue right now i just was wondering if there was a ready reference guide or an article that covered the basics. Seems like the question is asked a lot and it would be a benefit to have something like a checklist or something.

 

[Bart B.]

Here's a link to another thread on ES and SD:

http://forum.accurateshooter.com/th...-spread-is-acceptable-in-competition.3960990/

Anything statistical on this forum is like that on others. Lots of opinions and fallacies, few facts.

 

[dcali]

In my experience this is a problem that solves itself with proper powder selection and the use of a mild primer. I shoot a lot of .308 with varget in small primer brass and it’s never an issue.

 

[mgunderson]

My opinion, with some many possible calibers it is difficult to have a "standard" process for ES and SD. One caliber may shot sensitivity to X variable and another may not. Lots of good experience here with different shooting sports and calibers.

That's why people generally ask for specifics.

 

[Bart B.]

One opinion is 6 shots is enough to get ES because the number gets smaller with more shots.

 

[AJC]

One opinion is 6 shots is enough to get ES because the number gets smaller with more shots.

I'm confused how does extreme spread ever get smaller. I can understand it staying the same or growing. Please explain it getting smaller.

 

[Bart B.]

I'm confused how does extreme spread ever get smaller. I can understand it staying the same or growing. Please explain it getting smaller.

Here's someone who claims 6 shots is the limit to see ES. he shows a curve with ES getting smaller after 6 shots as I interpret it.

Range Statistics - ballistipedia.com

 

[dcali]

That’s just the confidence in group size based on the number of shots per group. The highest confidence turns out to be about 5 to 6 shot groups.

If you want to have higher confidence in your velocity numbers, more shots is always better.

Edit: to be clear, that’s highest confidence per shot fired.

 

[dmoran]

Here's someone who claims 6 shots is the limit to see ES. he shows a curve with ES getting smaller after 6 shots as I interpret it.

@Bart B.
Wow.... your not even close to being on the same page.... lol... but you have me laughing !.!.!

You should click on the link that I provided to that "Relative Efficiency" chart (HERE) and read. Depending on your reading ability, it may aid you in your confusion of what I posted on that other thread, as well as possibly change how you interpret it.... lol

 

[MislMan]

I must be missing something here. Extreme spread is the difference between two (2) data points, the lowest and the highest (smallest/largest)
This could be 100 shots with 99 data points between 1 and 2 but the 100th shot at 50. Extreme spread is 50. Standard deviation (SD) would vary based on the aggregate of the 100 shots.

 

[Bart B.]

@Bart B.
Wow.... your not even close to being on the same page.... lol... but you have me laughing !.!.!

You should click on the link that I provided to that "Relative Efficiency" chart (HERE) and read. Depending on your reading ability, it may aid you in your confusion of what I posted, as well as possibly change how you interpret it..... lol

Gotcha, didn't I.

Entrapment worked again.

 

[dmoran]

Gotcha, didn't I.

Entrapment worked again.

 

[dcali]

I must be missing something here. Extreme spread is the difference between two (2) data points, the lowest and the highest (smallest/largest)
This could be 100 shots with 99 data points between 1 and 2 but the 100th shot at 50. Extreme spread is 50. Standard deviation (SD) would vary based on the aggregate of the 100 shots.

Yes, but your confidence in the Es of 100 data points is going to be much higher than the one with 2 data points. And neither one is ever going to get smaller with more points.

 

[AJC]

So I am going to make some guesses and then people can tell me I am wrong. So if your es is say above 50 in a 10 round test do the following.
1. Verify your scale for powder does not suck
2. Check case capacity by any means
3. Try a different primer
4. Try a different powder
5. Try annealing your cases
So this may be way out of the box but that's why I am asking.

 

[Toby Bradshaw]

And neither one is ever going to get smaller with more points.

The estimate of standard deviation can get smaller with more data. Here's an easy example: if the first 2 data points happen to be at the opposite extremes for the dataset as a whole, the estimate of SD will become smaller as more data are added.

 

[Mulligan]

So I am going to make some guesses and then people can tell me I am wrong. So if your es is say above 50 in a 10 round test do the following.
1. Verify your scale for powder does not suck
2. Check case capacity by any means
3. Try a different primer
4. Try a different powder
5. Try annealing your cases
So this may be way out of the box but that's why I am asking.

If you had that much of an ES, I would make sure you are in a “node” with your powder charge. See this ladder testing procedure http://forum.accurateshooter.com/threads/ladder-testing.3894169/

If you are out of a node, you can have very drastic increases in velocity with small changes in powder.

If you are really trying to split hairs, consider sorting everything including primers.

CW

 

[Joe Salt]

For one thing if you are adding in the first shot out of the rifle after cleaning you Es. is going to be way high! I don't start my chronographing until I have a least six rounds down the barrel till it settles in. then start your count.

Joe Salt

 

[Bart B.]

Multiply the group's ES size by the shot count decimal number to see what 95% of the shots fired for the load will be.

Shot count decimal numbers:
3 shots, .40 to 2.5
5 shots, .60 to 1.52
6 shots, .65 to 1.40
10 shots, .80 to 1.23
20 shots, .88 to 1.12
30 shots, .92 to 1.09

Example:
1 MOA ES 5 shot group times .60 and 1.52, 95% of all the load's 5-shot groups will be between .60 and 1.52 MOA

1 MOA ES 30 shot group times .92 and 1.09, 95% of all the load's 30-shot groups will be between .92 and 1.09 MOA.

Same process for velocity ES.