Acceptable ES & SDs for Competition

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I finally had a chance to do some shooting over my chronograph this morning to find out exactly where my loads were at (a little slower than I had thought) and to do some testing for ES & SD.

I did tests using my normal load for the 200 Hybrids (.308) with 41.8 gr Varget and new, body sized, and once fired Lapua brass, and here's what I ended up with:

New Brass
Avg MV: 2535.8
ES: 16
SD: 6.06

Body Sized Brass
Avg MV: 2532.4
ES: 16
SD: 7.09

Once Fired Brass
Avg MV: 2526.4
ES: 20
SD: 7.53

I guess what I'm wondering is whether I should just call this good, or do I need to do some more work on trying to get the numbers down. The next obvious thing for me to do would be to start sorting cases and bullets I think. I've also got a new scale coming Monday (GemPro 250) which should hopefully help eliminate any variance caused by the +/- 0.1g on my current RCBS Rangemaster.

Any advice?
 
Hey FTRRookie

how is it going hope u will be at the Easterns. you are off to a pretty good start. under 8sd would be good for most applications. Sorry... "would be" you r close. Here is a extensive article on SD and target scoring. take a close look, this is a TR target...you're not that lucky shooting F class.. You need to have an SD of 4 or lower to stay within our 5 ring

http://home.comcast.net/~jesse99/palma.html

The scale should show you immediate improvements in es/sd numbers.

Best of luck
Trevor
 
What type of chronie are you using?

I gave up studying these numbers as soon as I found out the error in my chronie as indicated by the manf was HIGHER then the values I was trying to analyse.

Your generic Chronie has a 0.5% error in the clock - +/- 15fps on a 3000fps shot is the SAME reading. Pretty hard to interpret data smaller then the error in the device.

So I let the groups tell the tale.

[youtube]zIz50hQPyOY[/youtube]

300m just fast forward and you will see the group form

[youtube]SrhB29UIpJ4[/youtube]

500m Let the target tell you when a load is in tune.

Jerry
 
In the past I have found that low ES does not always correlate with small groups at short-mid range.

The ES and SD will come into play at the long range distances. Typically you are looking for numbers under 10 SD (under 25fps ES) so your numbers seem to be right in there.
 
For those that don't know how to find the SD (Standard deviation) this is how I do it. Feel free to chime in if you have a different way.

1.Fire a string of shots over a chrony and record you speed for each shot.For this example lets use ten shots.
1.3012
2.3022
3.2999
4.3007
5.3011
6.2998
7.3008
8.3002
9.3031
10.3014
2.Find the average of those 10 shots. Do this buy adding the speeds of all the shots together and then divide it by the number of shots you fired.In this example divide by 10.
1.3012
2.3022
3.2999
4.3007
5.3011
6.2998
7.3008
8.3002
9.3031
10.3014

Total 30,104/10
3010

3.Now using the average speed (3010),calculate the number of fps it would take to either add to get to your average or subtract from to get to your average.

1.3012=2
2.3022=12
3.2999=11
4.3007=3
5.3011=1
6.2998=12
7.3008=2
8.3002=8
9.3031=21
10.3014=4

4.Now take those numbers and find the average by adding them and dividing by the number of shots.

1.3012=2
2.3022=12
3.2999=11
4.3007=3
5.3011=1
6.2998=12
7.3008=2
8.3002=8
9.3031=21
10.3014=4

Total 76/10= SD of 7.6

5. To find the ES(Extreme Spread) count the number of fps between the slowest and fastest shots

Slowest was 2998
Fastest was 3031

ES= 33
 
I am not competative, I just #### around. But I did come to my own conclusions similar to Richard above. My goals are to keep ES in the mid twenties or less. SD 10 or less. But I usually only use the chrono after I have found my accuracy node. The measuring is just for confirmation and piece of mind.

For what its worth my bigger magnum SDs are in the 6's and my 223 SD hovers in the 10s. The 223 shoots the best so far. Case size, think percentage powder variations, can effect consistant results. I always shoot a minimum of 10 rounds and sometimes 20 over the chrony. Generally, the more rounds you shoot the more the ES grows. So I'm not sure if ES is really that useful overall.

Just my two half pennies.

I use online easy calc. But only because the user interface on my Chrony is terrible.

easycalculation.com/statistics/standard-deviation.php
 
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So when does the math get manipulated to the 80% SD?

Remember, in any bell curve, there are highs and lows that many statistians would discount and look at the central part of the curve.

How about one bad chronie reading that is 20fps off due to light, shadows, whatever?

In a 10 shot sample size, you just blew 10% of your data and have messed your math substantially. Horrors if you only shot a 5 shot string.

Etc, etc, etc.

Shoot at a target 200 to 300yds away. Deviations are abundantly clear.

I only use the chronie to make sure I am not going to blow myself up but beyond that, I don't bother with the math.

Try this simple test. Make up a batch of 20rds as precisely as you can.

Shoot 5 shots at 8am, 12noon and 3pm. Leave EVERYTHING is the same position and just compare your data. Shoot another 5rds on a different day.

Interesting....

Jerry
 
Yeah I agree the chrony has limitations however it is a decent method to see if you are on the right track with your reloading. Especially if you are just starting out.
 
Thanks for all the feedback guys. I'm pretty happy with the accuracy of this load and it doesn't sound like I need to pull my hair out trying to wring out the very lowest numbers I can just yet. I'm going to run the test again at 300y with the new scale and doing some sorting and see where I end up.

Out of curiosity, for those of you that do sort bullets do you do weight first, then base to ogive, or does it matter?

Trevor, I'll definitely see you this weekend. I may help Barry out with registrations/weighing-in on Friday so hope to see you there.

Cheers,

Scott
 
Best use for chrono data is to plug into JBM and figure out your drops.

I used to over-analyze the numbers untill I realized what others have already said, the precision of the chronograph makes ES and SD numbers totally unreliable.

Proof is on the paper. Trust you group sizes.
 
Jordan Smith said:
The problem is that you're using a Chrony ;)

Try a ProChrono Digital, and if you have the coin, an Oehler or a MagnetoSpeed is even better.
Click to expand...

The CED's are getting solid reviews too BUT ES and SD will NOT tell you anything about accuracy downrange.

You still have to shoot paper to find out.

If by some miracle you have 2 loads that shoot the same but one has smaller numbers, by all means go with the better math BUT I have yet to see this is real world shooting.

Some of my best loads don't like chronies...

YMMV.

Jerry
 
Mystic Precision said:
The CED's are getting solid reviews too BUT ES and SD will NOT tell you anything about accuracy downrange.

You still have to shoot paper to find out.

If by some miracle you have 2 loads that shoot the same but one has smaller numbers, by all means go with the better math BUT I have yet to see this is real world shooting.

Some of my best loads don't like chronies...

YMMV.

Jerry
Click to expand...
I'm certainly with you, there. I'm just pointing out that a chronograph can be a useful tool if you have one that has minimal error.
 
I have all the toys, just dropped a big swack on a real nice lathe etc etc. I still say the most important indication of accuracy is a good score. Like I always say, if it shoot it shoots! My favourite is being asked to bore scope a barrel, it proves nothing! If it shoots it shoots!! Doesn't matter the bc or the fps, if it shoots it shoots! Scores are the only thing that matter!!
 
True enough. When ironing things out as a new shooter, say for example you've never reloaded before and now your trying your first batch of handloads, do folks think a chrony is a somewhat useful tool in trying to figure out if you are on the right track?
 
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