Understanding ES and how to fix it

[philsummers21]

Ok. I'm fairly new to long range shooting. But I'm getting very hooked. Im not new to reloading but am new to reloading for long range. With my 22-250 I'm having an ES of 20-30 fps in 5 shot groups. I've played with powder charges and seating depth and blah blah blah. But when I get low ES my groups open up. So how do you find that balance. Plus what's good ES. And at what range does it really start to play a factor. I know it's a 22-250 and won't shoot extreme distances. But so far I've found a load I really like, shoots well. But has around 20 ES Here is my 100, 200, 300 groups

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[rcoody]

Sometimes ES and SD are overrated

With groups like that I wouldn't worry about it

Now it might show up at 600 or 1000 yrds but you aren't going there

 

[SHRTSHTR]

What chronograph are you using?

Ray

 

[philsummers21]

Yeah I'm thinking about 800 will be the limit on the 22-250. And that'll be on a coyote. Might try some prairie dogs out that far but that's a small target so.
It's the new Caldwell one that's upside down
http://www.btibrands.com/product/ballistic-precision-chronograph-g2/?mobile=true

 

[philsummers21]

But I am curious tho as I have a 30-378 wby I've been playing with that I'd really like to stretch it out and see what it and I can do at 1000+

 

[Trnelson]

I tend to put more weight on a lower SD. ES documents your outliers. SD is the difference from an average which holds more weight as it is most relevant to consistency. Lower your SD and your ES follows. 20 FPS ES may yield a decent SD with a large enough sample size to validate it.

 

[Wachsmann]

I tend to put more weight on a lower SD. ES documents your outliers. SD is the difference from an average which holds more weight as it is most relevant to consistency. Lower your SD and your ES follows. 20 FPS ES may yield a decent SD with a large enough sample size to validate it.

I started doing the same thing this last year as well. Wasn't worried as much with my ES as more worried about my SD. As I shot groups and reviewed notes I found one thing that dropped my SD and ED. Kind of weird but maybe since I don't have an brass anneal machine the residue from cleaning is acting as a lubricate such as graphite would. I was doing the wet cleaning with stainless pins. Tried 2 separate batches one cleaned with water and soap and the other in the old vibration cleaner. The one in the vibration cleaner was my on mix of dry treated (RBS red) walnut, rice, and corncob. It had lower ES and SD. Also produced a tighter group with less fliers. So this is how I clean my brass now. Every one in a while maybe after 5 shooting I use the wet cleaner to check the brass on the inside. Just gives me better visual inspection. After drying I run it in the vibration tumbler a for about an hour to get the same light amount of dust back in the necks. Also working on building me a brass annealing machine as well.

 

[rcoody]

What chronograph are you using?

Ray

Yep

The real keys to low sd's is neck tension and a very accurate powder.charge. of course many other things come into play

Only way to keep neck tension constant is annealing

But really I have had many great shooting loads with not so good sd's

Now for consistent accurate long range loads it is a must

 

[dsculley]

If the numbers from your chronograph are important to you, pay more attention to SD than ES. Your TRUE ES for that load is six times the standard deviation!

Personally, I tend to believe my target more than my chronograph. Is there a lot of vertical in the rounds fired? If not, it really doesn't matter what your chronograph said, the load is good. Personally, if I have a load shooting as well as the one you pictured, I would not worry about what my chronograph said. Mostly, I use the chronograph to keep me out of trouble. The first sign of over pressure you will see are muzzle velocities that exceed documented max velocities. When you see that it is time to back off. Once I choose a load, I don't use my chronograph much. I just prove that load on targets. As long as the load shoots well out to my expected max range I am good to go. Of course, "shooting well" can vary from person to person and from application to application.

To get good data from the chronograph, you need more than a few (3-5) rounds through it. While this is academic, I can generate velocities for two different 10 round strings that have the same ES. The SD of the strings will be drastically different based on whether they group around the center or around the extremes of the spread. If you evaluated them on ES only, you would conclude they are equal but that would be an error.

FWIW

 

[kyron]

Let me just point out that 20 ES is an awesome number. Because that means that your maximum deviation from the median is 10. Your standard deviation is also but guaranteed to be less than that and less then 10 SD is the goal of serious competitive shooters.

 

[philsummers21]

Thanks guys for reassuring me that I'm most likely good. I don't count on my chrono for a whole lot but I do look at it. And I only chrono when working up loads or if I'm just bored. I'll keep stretching it out and see what it can do.