Es and Sd troubleshooting flow chart

[Ccrider]

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.

The first thing I would check is neck tension. I believe brass prep and neck tension matter more than anything you list.

 

[Ccrider]

Btw, I have already seen enough to know that at short distance, single digit Es does not necessarily mean smallest group.

Of course, I don’t claim to know much. Just learning.

 

[Bart B.]

Btw, I have already seen enough to know that at short distance, single digit Es does not necessarily mean smallest group.

True, and positive compensation for muzzle vertical whip with a tuning weight neutralizes velocity spread. Not always 100%, but enough to work well.

It can fine tune barrels at short ranges too.

 

[Bart B.]

The first thing I would check is neck tension.

Measure how much pull in pounds it takes to get the bullet out of the case. This is what's important. 10% spread is good.

 

[AJC]

Measure how much pull in pounds it takes to get the bullet out of the case. This is what's important. 10% spread is good.

I would say that the average reloader does not have a way to do this. I dont think I do.

 

[Bart B.]

I would say that the average reloader does not have a way to do this. I dont think I do.

A 10 pound hand scale (trigger pull scale?) and a collet bullet puller. Clamp a shell holder in a bench vise.

Test with 10 resized cases before priming and charging

 

[243Mendoza]

@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

Good paper, thanks!

That paper is saying that if your looking for range statistic like extreme spread, 6 or 7 shot groups are optimum. That does not mean you shoot only ONE group but a BUNCH of 6-7 shot groups depending on the desired confidence level.

 

[dmoran]

@steve_podleski

Bare in mind I did not post that to this thread. Bart B. quoted me from a different thread, here.

Regardless.... You are correct....

 

[JimSC]

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.

I agree. I have only been doing this for a year or two now so keep that in mind but I have found finding the proper powder/primer combo will solve 99% of any velocity consistency issues. I just swapped the barrel on a .260 Remington and had to totally rework my loads. The old barrel was a 26 inch Criterion that loved 4831SC and had a flat velocity curve from 44.0 gns up to 44.6 gns with 140 gn bullets and CCi primers. The new 30 inch Shilen gave horrible numbers with 4831SC but absolutely loves H4350 with Remington 9 1/2s with everything from 120 to 140 gn bullets. Just swapping primers has gotten me from double digit to single digit performance with the same powder and bullet in my rifles

 

[243Mendoza]

Multiply mean 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.

Not sure if "mean ES size" is a contradiction unless it requires shooting a bunch of groups and not one group as shown in http://ballistipedia.com/index.php?title=Range_Statistics

 

[Bart B.]

Not sure if "mean ES size" is a contradiction unless it requires shooting a bunch of groups and not one group as shown in http://ballistipedia.com/index.php?title=Range_Statistics

No, just one group. I edited that post.

Thanks for your comments.

 

[Rico-chet]

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

My apologies for reviving this very old thread, but I'm having trouble finding the link Mulligan added. Is it saved as a different thread possibly? I keep getting a "Error 404 Not Found" message.
I tried the search but it didn't help.

R