SD and ES; what is considered good?

[supratt96]

I just started using a chrono and collected some SD and ES data for some of my pet loads. However, I'm not certain what constitutes good SD and ES in terms of long range shooting.

Could I get some feedback from th more educated on this?

Thanks.

 

[turbo54]

Re: SD and ES; what is considered good?

The best ES and SD are the ones associated with the best groups.

In general, ES under 20-25 and single digit SD is "good", although I have loads with "bad" statistics that group better than loads with "good" statistics. Dont put too much weight on your stats. Go with what the target tells you.

FWIW: I had a ten shot group today post an ES of 8 and an SD of 1. If you drive the rifle right, this load will leave one 30 caliber hole in the target at 200 yards, regardless of how many times you pull the trigger.

 

[diriel]

Re: SD and ES; what is considered good?

Single digit ES numbers only really make a difference at ranges beyond about 400ish, and especially as you hit about 800 and beyond. The reason being, of course, if one shot is at 2620, and the next shot is at 2700, then you will get Vertical Stringing due to the velocity difference as the ranges extend out.

Have a good one,
Gary

 

[MitchAlsup]

Re: SD and ES; what is considered good?

ES under 40 is good
SD under 15 is great

 

[vman]

Re: SD and ES; what is considered good?

ES of 10 and SD of 1 is what you want

 

[supratt96]

Re: SD and ES; what is considered good?

Thanks for the feedback. Looks like I'm doing ok. All of my pet loads were well within the "great" range. My best did an ES of 6 and a SD of 3. I may never get a 10/1, but I can live with that, lol.

 

[vman]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lakeway</div><div class="ubbcode-body">Thanks for the feedback. Looks like I'm doing ok. All of my pet loads were well within the "great" range. My best did an ES of 6 and a SD of 3. I may never get a 10/1, but I can live with that, lol. </div></div>

Man thats pretty good... You really cant complain about that at all.

 

[Jeffvn]

Re: SD and ES; what is considered good?

ES under 30; SD under 13 are "acceptable' for shooting steel
ES under 20; SD under 10 are "good" for 1,000 yard F-Class

JeffVN

 

[jlow]

Re: SD and ES; what is considered good?

I think one thing that has been missing in this discussion is “N size” i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless.

 

[shoepop]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">I think one thing that has been missing in this discussion is “N size” i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless. </div></div>

Agree, I think at a minimum 4 5 shot strings over chrono are needed same with accuracy testing.

 

[9H_Cracka]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">ES under 40 is good
SD under 15 is great </div></div>

Sucky and suckier.

Single digit SD and sub-20 FPS ES is what is needed to hold 1 MOA elevation at 1k with a 308.

I and fellow long range competitors routinely experience single digit ES.

 

[supratt96]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">I think one thing that has been missing in this discussion is &#147;N size&#148; i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless.</div></div>

In this case "N" = 10 shot strings. I will shoot some longer strings next time and see how the numbers look.

 

[clmayfield]

Re: SD and ES; what is considered good?

As with group size, your SD is going to depend on number of shots. I use 20+ shots to calculate SD and I get just under 10. If I were doing 5 shot SD's, I would have around a 6 or 7. ES has no real statistical meaning and is even more dependent than SD on number of shots.

 

[jlow]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lakeway</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">I think one thing that has been missing in this discussion is &#147;N size&#148; i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless.</div></div>

In this case "N" = 10 shot strings. I will shoot some longer strings next time and see how the numbers look. </div></div>

Sorry but am I the only one who is finding this a bit hard to swallow? You are saying your ES (extreme spread) = 6 and SD (standard deviation) n= 3 for a 10 shot group? That is freaking hard to believe because I shot a seven shot group (actually 10 but don’t have numbers for 3) of FPGMM out of a LaRue OBR and my ES = 87 and SD = 31. (average MV = 2532 ft/sec).

Now I am not saying that this is the most consistent ammo in the world but it certainly is not bad stuff, but for your rounds to be basically one order of magnitude better…..

 

[KevinU]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lakeway</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">I think one thing that has been missing in this discussion is &#147;N size&#148; i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless.</div></div>

In this case "N" = 10 shot strings. I will shoot some longer strings next time and see how the numbers look. </div></div>

Sorry but am I the only one who is finding this a bit hard to swallow? You are saying your ES (extreme spread) = 6 and SD (standard deviation) n= 3 for a 10 shot group? That is freaking hard to believe because I shot a seven shot group (actually 10 but don’t have numbers for 3) of FPGMM out of a LaRue OBR and my ES = 87 and SD = 31. (average MV = 2532 ft/sec).

Now I am not saying that this is the most consistent ammo in the world but it certainly is not bad stuff, but for your rounds to be basically one order of magnitude better….. </div></div>

Believe it, it's true. This is why we hand load. My load for my rifle, 10 shots SD 5.4.

 

[jlow]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KevinU</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lakeway</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">I think one thing that has been missing in this discussion is &#147;N size&#148; i.e. the number of rounds used in the calculations. Without this number, the ES and SD numbers are pretty meaningless.</div></div>

In this case "N" = 10 shot strings. I will shoot some longer strings next time and see how the numbers look. </div></div>

Sorry but am I the only one who is finding this a bit hard to swallow? You are saying your ES (extreme spread) = 6 and SD (standard deviation) n= 3 for a 10 shot group? That is freaking hard to believe because I shot a seven shot group (actually 10 but don’t have numbers for 3) of FPGMM out of a LaRue OBR and my ES = 87 and SD = 31. (average MV = 2532 ft/sec).

Now I am not saying that this is the most consistent ammo in the world but it certainly is not bad stuff, but for your rounds to be basically one order of magnitude better….. </div></div>

Believe it, it's true. This is why we hand load. My load for my rifle, 10 shots SD 5.4. </div></div>

I also hand load but have never seen that kind of number. So what is the secret?

 

[Chiller]

Re: SD and ES; what is considered good?

What exactly causes the spreads?
Assuming that I am loading the "same" amount (.02 grain or there abouts) what causes the spread?
If the barrel length is long enough one would assume there is time for the powder to be all burned. Also assuming that the primers all came from the same lot.

The next question that is related to this what has the greatest contribution to accuracy? COAL and the associated jump or same powder load?

 

[jlow]

Re: SD and ES; what is considered good?

Unfortunately, there are a multitude of factors that can cause the spread. This includes the shape and internal geometry of the brass, burrs on the primer pocket, neck tension, variability in the primer, powder, bullet, barrel, bullet seating depth, concentricity, etc they can and will affect the spread. Just in case you ask is it not the same barrel, the answer would be are you sure that every bullet travelling down the same barrel encounters exactly the same surface? The list is endless…..

 

[supratt96]

Re: SD and ES; what is considered good?


I also hand load but have never seen that kind of number. So what is the secret?[/quote]

There is no secret. However, I have been reloading a long time and like anything else, practice makes perfect. I just never bothered to use a chronograph before. I simply judged how consistent a load was by the results it gave me.

If there is anything special that I believe makes for highly consistent ammo, it is this; I anneal every other loading to maintain consistent neck tention and I measure every powder charge to 1/100th of a grain with a professional jewelers scale. The rest is just the basics and the discipline not to cut corners.

As far as your results with FPGMM, I can't comment. I haven't used factory ammo in 15 years.

 

[mizer67]

Re: SD and ES; what is considered good?

I use a sample size of 50 rounds to get ES and SD. The smaller the sample size gets, the less meaningflu the result.

In 5.56mm chambers, using SMKs, 7 1/2s or FGMM primers and Lapua brass, I have never achieved a single digit ES.

ES of 28 and SD of 10.2 is the best I've seen. I believe the answer to the question depends largely on the size and the caliber involved. Achieving single digits in .223 is harder than .308 for instance, in my experience.

Also, I can pull up a number of 10-round strings with single digit SDs in 5.56mm / .223, but that tells me nothing about the performance of the load as a whole. The sample size is too small and your target needs to do the talking.

 

[shoepop]

Re: SD and ES; what is considered good?

I don't get my panties in a wad over the #'s. If I can get 1/2 MOA vertical @ 600 I call it GTG.

 

[Hummer]

Re: SD and ES; what is considered good?

When the Marine Corps Rifle Team was using M14s I asked their ammo tech what their internal requirements were for LR ammo and they said SD of 10 was their standard.

A 30 cal bullet at 1000 yards with a 100 FPS spread will give you about 40" of vertical stringing. The 10 ring is 20" so if you are absolutely a machine rest holder you could theoretically get my with a ES of 50 FPs and get them in 10 ring. The X ring on high power "C" target is 10" so if you want to get a bunch of Xs you better figure on ES of 25 fps.

If you have heart beat causing vertical rifle movement then you better figure on ES of 10 FPS.

If you are shooting F class you better figure on 10 fps ES.

Once you arrive at this chronograph 25 continious shots and see how you do. You may find an increase or decrease in velocity once the barrels gets warm and if your barrel is not stress relieved then it may warp when it gets warm which is always good for some choice words in the middle of the string.

 

[jlow]

Re: SD and ES; what is considered good?

It’s not a question of getting one’s “panties in a wad”, it is simply trying to understand the limits of what is possible. This is an important part of learning anything including reloading. If we don’t ask and challenge, we will never benefit from someone else’s leanings.

I think a SD of 10 is a lofty goal but potentially doable, but an SD of 3 from a 10 shot group (done consistently) seems hard to believe (not saying it cannot be done, just hard to believe). For example, an ES of 6 from the same quote say from an MV of 2500 ft/sec means that <span style="font-weight: bold">NONE </span>of the rounds deviated more than 0.24%! Now I can certainly weigh powder that accurately with my electronic scale, but to have a sum deviation from <span style="font-weight: bold">ALL </span>the components involved in my reloading to not deviate by that much would be daunting. Not saying it cannot be done, just daunting and takes more than just your everyday precision reloading practice.

The fact is any one of us that states on any board numbers that are that good is going to get challenged. It does not mean that it did not happen; you just have to be able to come up with something equally convincing to justify the numbers.

 

[vman]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jlow</div><div class="ubbcode-body">It’s not a question of getting one’s “panties in a wad”, it is simply trying to understand the limits of what is possible. This is an important part of learning anything including reloading. If we don’t ask and challenge, we will never benefit from someone else’s leanings.

I think a SD of 10 is a lofty goal but potentially doable, but an SD of 3 from a 10 shot group (done consistently) seems hard to believe (not saying it cannot be done, just hard to believe). For example, an ES of 6 from the same quote say from an MV of 2500 ft/sec means that <span style="font-weight: bold">NONE </span>of the rounds deviated more than 0.24%! Now I can certainly weigh powder that accurately with my electronic scale, but to have a sum deviation from <span style="font-weight: bold">ALL </span>the components involved in my reloading to not deviate by that much would be daunting. Not saying it cannot be done, just daunting and takes more than just your everyday precision reloading practice.

The fact is any one of us that states on any board numbers that are that good is going to get challenged. It does not mean that it did not happen; you just have to be able to come up with something equally convincing to justify the numbers.
</div></div>

If you individually weigh sorted cases, and then further into internal case volume, used the right primers, sat smack bang in the middle of a node, measured powder charges out with kernal accuracy, weight sorted projectiles and also further sorted into bearing surface length... Then yes its actually easily possible.

 

[AKAce]

Re: SD and ES; what is considered good?

While ES / SD are important numbers when working a load... the numbers are Relative !

Chrono's are not exact, even the best ones (realistically used at the range) give dif readings in dif lighting conditions etc. They give you a good idea of velocity and a good idea of the ES / SD... but are more accurate in Comparing one load to another in the SAME conditions.

Most of my loads on a overcast day with no shadows have a ES between 10 and 25 (20 Shots Min) Let the sun come out and that may go Up or Down depending on the angle.

True Velocity comes from crunching numbers on Actual Dope.
True ES / SD comes from crunching numbers on actual vertical spreads at distance.

Not all Chrono's are created equal !

 

[jlow]

Re: SD and ES; what is considered good?

Some of what you mentioned are not really exotic techniques, but I would like you to expand a bit on “further into internal case volume” and “sorted into bearing surface length”.

Since it is easily possible, if would help us if you could you show us specific examples of MV and group size date that you have personally generated.

 

[jlow]

Re: SD and ES; what is considered good?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ~Ace~</div><div class="ubbcode-body">While ES / SD are important numbers when working a load... the numbers are Relative !

Chrono's are not exact, even the best ones (realistically used at the range) give dif readings in dif lighting conditions etc. They give you a good idea of velocity and a good idea of the ES / SD... but are more accurate in Comparing one load to another in the SAME conditions.

Most of my loads on a overcast day with no shadows have a ES between 10 and 25 (20 Shots Min) Let the sun come out and that may go Up or Down depending on the angle.

True Velocity comes from crunching numbers on Actual Dope.
True ES / SD comes from crunching numbers on actual vertical spreads at distance.

Not all Chrono's are created equal ! </div></div>

All this sounds reasonable to me - thanks!