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Ignoring ES/SD numbers.....

JRose

JRose

Gunny Sergeant
Full Member
Minuteman
Jul 10, 2007
3,296
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Back in BHam!!!
#1
I cannot get good ES/SD numbers on any of my loads, yet they continue to be very accurate, even at range. When doing load development, sometimes I will get good ES/SD numbers on a particular load, but then it seems the most accurate load might not have the best numbers.

So I've said to hell with it and started ignoring them, is this a mistake?

Examples:

My CM load, it is 44.0 gr of RL-17 with a 139 hBN Scenar, is EXTREMELY accurate, but ES/SD numbers are not real desirable.

My .243, 47.5 gr RL-25 with a 115 hBNDTAC, developed by George, is a hammer... Shitty ES/SD numbers....


:?
 
#2
Re: Ignoring ES/SD numbers.....

What are shitty ES/SD numbers? I have been able to produce single digit SDs with most rifle loads. What kind of SDs are you getting?

I would say that the target can't lie and if you're getting the accuracy, to not worry too much, but the reality is that at long distance, consistent velocity is way more important than how tight your groups are at 100 yards, or so it would seem.
 
#3
Re: Ignoring ES/SD numbers.....

JRose,

ES/SD are not too make or break out to about 300 yards, give or take a little depending on what you are shooting.

The best way to answer your question would be for you to fire up a ballistic calc program and input your bullet / load info Minimum Velocity, then look at the numbers. Next up, do this again but input the max velocity and look again at your windage and drop numbers. That will tell you the story in hard cold numbers.

Good Shooting,
Gary

http://www.jbmballistics.com/calculations/calculations.shtml
 
#5
Re: Ignoring ES/SD numbers.....

I have found that a lot of low numbers has to do with preparation before assembly of the loaded rounds. Care in case prep as well as primer seating, powder measuring, as well as neck tension and seating the bullet all have a hand in keeping the numbers close.
 
#6
Re: Ignoring ES/SD numbers.....

I only have one chrono, it's a CED.

Numbers are roughly SD's in the teens and ES's in the 30's-60's in some cases.

I'm pretty retentive about brass prep, I don't get all bench resty and turn necks, or weigh cases. I beam scale each powder charge.
 
#7
Re: Ignoring ES/SD numbers.....

CED is a pretty fair name in chronographs. The next one I get is looking to have that name.

Standard Deviation numbers in the twenties and teens are NOT crappy numbers. Some powder / primer combinations can not get single digit numbers. But some of the most accurate 600 yard loads I have ever shot had mid teen Standard Deviation numbers.
 
#8
Re: Ignoring ES/SD numbers.....

I wouldn't worry for a second if a load that had SD's in the teens and ESs in the 30s was shooting well. So many other factors to screw you up, that's not one of them.

Shoot on.
 
#11
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body">maybe you just suck and should quit pretending you are a reloader</div></div>



or get a prometheous
 
#13
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body">maybe you just suck and should quit pretending you are a reloader</div></div>



or get a prometheous </div></div>

1: too expensive

2: you can't even buy the damn things if you do want one.
 
#15
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body">NOW you're a hater too ? </div></div>

Oh, I ain't hating... I'd LOVE to have one, I think they're cool as hell, and I can respect anything that champions fine craftsmanship and extreme accuracy, but it is what it is.
 
#16
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body">

or get a prometheous </div></div>

1: too expensive

2: you can't even buy the damn things if you do want one. </div></div>

I would love to buy/borrow/rent/steal a ProII sometime just to see what, if any, difference it made in ES and SD as compared to my RCBS chargemaster or Hornady LnL with no other changes to loading technique, if for no other reason than to evaluate the rest of my loading process.
 
#17
Re: Ignoring ES/SD numbers.....

SD in the teens? That ain't good - figure 4x SD for practical ES over a long string - 6x if you want to scare yourself. It shouldn't be that tough to get SD down to 10-12 or below - even without benchrest stuff and certainly doable without a Prometheus.

If the load shoots good at distance, I'd say check the usual culprits... fresh battery in the chrono, make sure the light isn't coming in from a steep angle, try to avoid days with intermittent clouds if not using IR, etc. basically try to do the testing when the lighting conditions are as close to optimal, and consistent, as practical. If the load is a little loose @ long range, maybe the problem *is* at the loading bench. Check your loading area to make sure you don't have any stray drafts, try a few basic things like brushing the case necks out, maybe check how many times your cases have been fired - neck tension can get screwy when they need annealing, etc.


That said... once upon a time I ran across a powder/bullet combination that shot okay (for HP Service Rifle) but gave just the most atrocious ES/SD numbers. Finally resigned myself to burn it up in practice and use good stuff for matches.

My 'final' test runs for a good load usually net SD somewhere 10 or under (6-8 is pretty common) and 20-30fps ES. My 'final' tests are 20-25 shot strings, though. I do a lot of the 'benchresty' stuff as far as load prep... but my experience is that a *good* load is fairly tolerant of all the miscellaneous BS, but it is possible to have loads that shoot very well but are somewhat 'tweaky' that will drive you to distraction trying to keep them in tune.
 
#19
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body">Numbers are roughly SD's in the teens and ES's in the 30's-60's in some cases.
</div></div>

Really, you have little to worry about! Really. I know many experienced shooters that would LOVE to have their SDs consistently in the middle teens. It is exceedingly and excruciatingly hadr to get SDs down into the low teens.

ESs in the 30-40s is just par for the course, 40-50 underperforms just a triffling--that means it would be very (very) hard to tell, by reading the target, that anything at the reloading station is amiss.

Perhaps all you need is a little more dilligence at the reloading station, at the scale, at the measurement devices, inroder to drive the SDs down, maybe better notes at the statioin or at the range. But my basic bet is that you are already producing ammo that is limited more by the shooter than itself, and more by the gun than by itself.

So, perhaps I should borrow a phrase from glass pushers* that might be appropriate, herein. "Shoot more, worry less."

* people who make their own lenses and mirrors.
 
#20
Re: Ignoring ES/SD numbers.....

Go plug your high and your low into your ballistic calculator for 1k yards Jay and compare the POI difference. Short range accuracy and long range POI repeatability are not the same thing.

Since you don't know which of your rounds are shooting the high number and which are shooting the low, say you shoot a low one, are below the target, the correct your elevation for the next shot, and shoot a high velocity one. Depending on the size of your target, you go from low to over the top. A major WTF moment in my shooting.
 
#21
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H</div><div class="ubbcode-body">Go plug your high and your low into your ballistic calculator for 1k yards Jay and compare the POI difference. Short range accuracy and long range POI repeatability are not the same thing.

Since you don't know which of your rounds are shooting the high number and which are shooting the low, say you shoot a low one, are below the target, the correct your elevation for the next shot, and shoot a high velocity one. Depending on the size of your target, you go from low to over the top. A major WTF moment in my shooting. </div></div>

Yeah, no shit. That is why my SD is 5fps and ES is 11fps. Tell Jason that.
 
#22
Re: Ignoring ES/SD numbers.....

Both loads mentioned produce consistent results both at long and short range. Like I said, I'm happy with the accuracy and performance of the ammo, I'm just curious as to why the numbers are high on good working ammo.

All that being said, I don't really shoot groups past 300y, but I'm target out at distance.

As far as prep work, I do it all now except weigh cases and neck turn. I weigh powder with a Charge Master, then trickle up to load on a Lyman M-5 beam scale.

I'm OK with just rocking on like things are, but like everything, I quest for better...
 
#23
Re: Ignoring ES/SD numbers.....

Don't sweat it.
If the load shoots well, your chrono's lying to you.

My usual 308 and 7-08 loads shoot as well as I can, and better when there's a tighter nut behind the trigger, but my chrono was telling me 30ish SD on the 308 and 20ish on the 7-08.

After much self induced worry, I had a chance to shoot over the Oehler 3 screen on an overcast day at the local sheriff's range-now I like my loads-308 is actually 13SD and 34ES and the 7-08 load is 07SD and 18ES.

The best thing I did for my consistency was to keep the brass sorted by # of firings.
 
#24
Re: Ignoring ES/SD numbers.....

I found one way to knock a few feet per second off your ES numbers is to put the B on the BR-2 Primers in the same spot on every case.

My gun for instance likes the B vertical right between the 260 and the REM.

YMMV
 
#25
Re: Ignoring ES/SD numbers.....

Now that is a bit much.....

Really, I'd buy the "B" deal if the primer's components were lined up all the same, but the anvils on a bunch of BR's I've got are random in their alignment to the "B".
 
#27
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body">I cannot get good ES/SD numbers on any of my loads, yet they continue to be very accurate, even at range. When doing load development, sometimes I will get good ES/SD numbers on a particular load, but then it seems the most accurate load might not have the best numbers.

So I've said to hell with it and started ignoring them, is this a mistake?

Examples:

My CM load, it is 44.0 gr of RL-17 with a 139 hBN Scenar, is EXTREMELY accurate, but ES/SD numbers are not real desirable.

My .243, 47.5 gr RL-25 with a 115 hBNDTAC, developed by George, is a hammer... Shitty ES/SD numbers....


:? </div></div>

One thing you didn't mention is what primers you are using.
I measured recently and haven't backed up my data so it may have been a Fluke.
But,
Same everything in my 260 load but changed primers.
BR2 was an ES of 17.57 and SD of 7.41
210GoldMetalMatch 43 ES and SD of 18.00
BR2 was 38FPS slower.

Something to consider if you haven't already.
 
#29
Re: Ignoring ES/SD numbers.....

how are you holding the rifle when shooting through the chrono? I found with mine I can intentionaly get numbers high or low depending on how much the rifle is allowed to move in recoil.
 
#31
Re: Ignoring ES/SD numbers.....

JRose,

Lets say your 115 DTAC load is 3150 nominal:
-- ES of 40
- Low load = 3130 FPS: drop @ 500y = -38.3" // Windage @ 10mph = 12.8"

Now:
- High load = 3170 FPS: drop @ 500y = -37.2" // Windage @ 10mph = 12.6"

Ballistic Calculators are your friend. Embrace them. Now you do not need to wonder so much. Just go out to the field and test to see how close the program really is. Now that you have an idea what to look for.

That is a fairly brutal load btw
smile.gif
I would hate to be your barrel!

Good Shooting,
Gary
 
#34
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Captain Kick-Ass</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H</div><div class="ubbcode-body">Go plug your high and your low into your ballistic calculator for 1k yards Jay and compare the POI difference. Short range accuracy and long range POI repeatability are not the same thing.

Since you don't know which of your rounds are shooting the high number and which are shooting the low, say you shoot a low one, are below the target, the correct your elevation for the next shot, and shoot a high velocity one. Depending on the size of your target, you go from low to over the top. A major WTF moment in my shooting. </div></div>

Yeah, no shit. That is why my SD is 5fps and ES is 11fps. Tell Jason that. </div></div>

Sorry I meant Jason.
 
#36
Re: Ignoring ES/SD numbers.....

Whatever, you crazy Acculab and Prometheus guys, I'll bet neither of you have kids. SD in low teens are perfectly acceptable for guys with kids who don't have hours a day to devote to 1 kernal reloading.
 
#37
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">That is why my SD is 5fps and ES is 11fps.</div></div>

If you really chronographed enough rounds to know that your SD is 5 fps, then your actual ES is more likely around 30 fps. You just didn't chronograph enough rounds to find the actual ES.

See:

http://www.shootersjournal.com./Features/Haps/EnglemanChronographStatistics.pdf
 
#38
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">That is why my SD is 5fps and ES is 11fps.</div></div>

If you really chronographed enough rounds to know that your SD is 5 fps, then your actual ES is more likely around 30 fps. You just didn't chronograph enough rounds to find the actual ES.

See:

http://www.shootersjournal.com./Features/Haps/EnglemanChronographStatistics.pdf
</div></div>

The Oehler 35P will give you average velocity, ES, and SD from just a single shot. Sure, it's expensive, but the money you save in ammo makes up for it fast...

the reason they aren't for sale anymore is the big ammo companies suppressed it to sell more ammo to people who thought they needed to run 20 or 30 rounds over a chrono to get ES and SD.
 
#40
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">That is why my SD is 5fps and ES is 11fps.</div></div>

If you really chronographed enough rounds to know that your SD is 5 fps, then your actual ES is more likely around 30 fps. You just didn't chronograph enough rounds to find the actual ES.

See:

http://www.shootersjournal.com./Features/Haps/EnglemanChronographStatistics.pdf
</div></div>

"Extreme Spread" has no statistical meaning. The use of 6 SD's in the article was arbitrary. The theoretical ES for a population is infinity, which is why we use SD for comparison.

And yes, more data points will give you a higher SD until around 30, at which points, sample SD roughly equals population SD. 15 shots is probably plenty. Just like with groups where there is a big difference between the group size of a 3, 5, and 10 shot group, there will be a difference in SD between a 5 shot, 10 shot, and 15 shot SD. Not many people do a 30 shot SD, but once you have developed a load, you can always practice through a chrony to get to 30 shots.
 
#41
Re: Ignoring ES/SD numbers.....

Sorry to hijack, but while we are talking statistics -- I've been curious if you have chrono data for your load over a bunch of rounds, what is the preferable way to choose the velocity value that you use for your ballistics software (ignoring temperature factors and such)?

Average? Toss out any "flyers" that might exist then take the average? Arithmetic mean?
 
#42
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ratbert</div><div class="ubbcode-body">
The Oehler 35P will give you average velocity, ES, and SD from just a single shot. Sure, it's expensive, but the money you save in ammo makes up for it fast...

the reason they aren't for sale anymore is the big ammo companies suppressed it to sell more ammo to people who thought they needed to run 20 or 30 rounds over a chrono to get ES and SD.
</div></div>

Holy cow, Ratbert. No offense, man, but are you serious?

The thing about 20-30 shots or 'samples' has to do with formal statistics (t-tests vs. normal distribution), and nothing to do with some conspiracy theory.

Monte
 
#43
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">
laugh.gif
LOL! That's funny - thanks for the grins!

Might as well just shoot one-shot groups, too - they'll be a lot tighter than those 5-shot thingies.

</div></div>

I wake up every day and say to myself "If only I can find some way to put a smile on Lindy's lips..."

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: memilanuk</div><div class="ubbcode-body">
Holy cow, Ratbert. No offense, man, but are you serious?
</div></div>

I worry about you.
 
#45
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I've been curious if you have chrono data for your load over a bunch of rounds, what is the preferable way to choose the velocity value that you use for your ballistics software (ignoring temperature factors and such)?</div></div>

Yeah, use the average - bearing in mind that about two-thirds of the rounds are going to be within one SD plus or minus of the average, and the rest will be outside that. There's just no way around that.

And see:

Sources of Ballistic Program Inaccuracies
 
#46
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">That is why my SD is 5fps and ES is 11fps.</div></div>

If you really chronographed enough rounds to know that your SD is 5 fps, then your actual ES is more likely around 30 fps. You just didn't chronograph enough rounds to find the actual ES.

See:

http://www.shootersjournal.com./Features/Haps/EnglemanChronographStatistics.pdf
</div></div>

You have no idea what I chronographed. Or how I get those numbers. I do know that you pooh-pooh anything that Brand Cole produces to the point of infringing his intellectual property.

So why don't you tell me what I did to come up with those numbers? You tell me what I have been doing with all my testing and where my numbers come from. Or are you going to cite some other person again and think that proves your point? Because it doesn't.
 
#47
Re: Ignoring ES/SD numbers.....

You wouldn't even question what I wrote if you knew anything about statistics. Since you obviously don't, I provided a reference, which you appear to have failed to read.

If you believe that your ES is twice the SD of you're load, you're ignorant.

Ignorance is curable, if one is willing. You appear not to be.
 
#48
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">"Extreme Spread" has no statistical meaning.</div></div>

That's true. The statistical term is "range".

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The use of 6 SD's in the article was arbitrary.</div></div>

Well, not really. In a normally-distributed population, about 99.7 percent of the population is found within +/- 3 SD of the mean.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The theoretical ES for a population is infinity, which is why we use SD for comparison.</div></div>

Umm, theoretically, perhaps, but not practically.

For example, if a bullet emerges from the muzzle, it's velocity has to be some minimum value, even if it's only 1 foot per second. At the other end, a load of Varget pushing a 175 SMK in a .308 is probably never going to exceed 3000 feet per second, because you can't get enough powder in the case to drive it faster.

So, the theoretical maximum range for that load is not more than 3000 fps. In practice, it's much less.

In the same way, human IQs have a maximum range. The highest ever reliably recorded was about 228, and the lowest is not zero, because below a certain IQ level, life is impossible.

So, ranges are rarely infinite, unless the population has the potential to be, which most don't.

But you're quite right that SD is a more useful figure of merit for shooting than ES.
 
#49
Re: Ignoring ES/SD numbers.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">You wouldn't even question what I wrote if you knew anything about statistics. Since you obviously don't, I provided a reference, which you appear to have failed to read.

If you believe that your ES is twice the SD of you're load, you're ignorant.

Ignorance is curable, if one is willing. You appear not to be.


</div></div>

uh huh, so where did I get those numbers?
 
#50
Re: Ignoring ES/SD numbers.....

You measured them with a chronograph, I expect, but if you'd read the reference, you'd know why that's not an indication of the <span style="font-weight: bold">true</span> extreme spread, or range, if you prefer, of your load.

If you chronographed one shot, you'd have an extreme spread of zero and an SD of zero. Do you think that would be the true SD and ES of your load? I hope not.

Read the reference. Here it is, again:

http://www.shootersjournal.com./Features/Haps/EnglemanChronographStatistics.pdf
 
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