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How important is ES and does it mean you have an accurate load?
Just working up loads for a 6.5x55 130 accubond at 2900 with an ES of 5 ,130 scirocco ES of over 20 both loads 3 shots into a ragged hole at 100 . Can't get a lower ES with the scirocco any idea why?
Pretty sure an ES of 20 is considered good.
The big test would be if the groups started opening up at long range, 1km type stuff.
I'd be more than happy with ragged hole groups and an ES on 20.
ES is only really important if you are shooting long range. Most of the cheaper chronos aren't accurate enough to for you to be able to get reliable ES data, average speed yes, but ES no.
One way to improve ES is to get consistent neck tension. Shawn Carlock mentioned that lubing the inside of the case neck with graphite improves ES. Get a container, put some lead shot in, put some graphite powder in, push the sized case down into the container, inside case neck lubed.
you probably wont notice velocity spread on a target at 100 if both the loads group the same, you need to run through a chrony. the only other way is to shoot targets at a bit of distance
loads were run through a oehler 35.
Here are the sort of things to consider in getting consistent neck tensionQuote:
Originally Posted by stug
Neck Tension — Not Just Bushing Size within AccurateShooter.com
The graphite lubing works reasonably well after cleaning cases with ultrasonics.
Your ES values will be good then. Sometimes a change of primer can help ESQuote:
Originally Posted by von tempsky fan
Not sure why, but I've always used SD rather than ES as a measure for reloading quality control. Once you get into single digit figure SD for 5 or more shot groups, your ammo is pretty decent.
Will be interesting to hear other folks opinions on SD vs ES.
I will try a different primer with the sciroccos and graphite lube the necks it should be interesting to see results.
The value of ES is knowing the worst case scenario, so this applies particularly to long range target shooting. A load with a reasonable SD will put most into tight elevation at long range BUT if the ES is bad, the odd shot will cop a bad score and it's nothing to do with your trigger pulling or wind calling. Serious target shooters can't live with that.
Your average deer shooter can happily ignore either metric and if they get a half reasonable group, they will easily put meat on the table.
ES or SD means shit if it won't group, I've had single digit loads shoot like crap & 20-30fps ES loads shoot mint, go figure....
Kirby reckons 20-40 fps ES you are GTG if any one should know it will be him if you are hunting.
Obviously in this case less is more, but isn't necessarily necessary...
I'd be happy with that.
Have a read of this guy's experience Shooting Australia - Canada 2002
Fair way thru he documents his long range load ES and SD. Doesn't weigh his charges, in fact cannot say how many grains - uses Harrell dispenser.
Shooting a minscule groups at 100yds can mean zip at long range. Litz has also covered off on the same topic.
Shot a few .15 groups with my 6.5x47 at 100yds but didn't even progress with the load to actual long range shooting as the ES was around 30fps.
Small ES means minimal vertical dispersion at long range.
Mute point obviously for hunting type accuracy requirements.
Chronograph some brands of factory ammo and the ES is shocking but then so is the accuracy.
Well here is something interesting, I just got a chrono so used it Friday. Only 5rnds as an initial trial so have to be careful reading too much into them.Quote:
Originally Posted by ebf
I dont think much of SD as a quality control thing. Take this set, the 37gr shot the most accurate followed by the 39gr with the 38gr the worst. Did I Ioad the 39grain badly? and the 38grain super badly? I dont see why that would be the case. Interesting thing is the 1943 case v winchester case, 1gr more in the winchester but the velocity is still slower, ergo less internal volume (I should go measure it). The SD gave me an indication of the best group, 37gr 2208 and that was repeated in the 69gr and 77gr, least SD best grouping.
SD (left column),
ADI 2208
28-8-2015
303brit
case 37gr SD
1943 1 2161 2161
2 2182 2182
3 2169 2169
4 2147 2147
5 2082 2082
10741 39.1241613329
2148.2
case
winchester 38gr SD
1 2103 2103
2 2202 2202
3 2082 2082
4 2078 2078
5 2161 2161
6 2097 2097
7 2214 2214
8 2097 2097
9 2163 2163
10 2072 2072
11 2111 2111
12 2112 2112
13 2080 2080
27572 48.030305604
2120.9230769231
1943 39gr SD
1 2220 2220
2 2307 2307
3 2249 2249
4 2385 2385
5 2294 2294
11455 63.0594957163
2291
===============
another set,
===============
case 69gr factory
adi smk 2684 2684
guncity std ammo 2710 2710
good accuracy 2701 2701
2676 2676
2701 2701
13472 13.9391534894
2694.4
69gr tmk 24.0gr
2530 2530
2535 2535
2547 2547
2517 2517
good SD 12.4197423484
10129
2532.25
69gr tmk 24.4gr
2560 2560
2615 2615
2615 2615
2609 2609
2583 2583
12982 24.265201421
2596.4
69gr tmk 24.8gr SD
adi case 2612 2612
2208 2598 2598
2572 2572
2591 2591
16.6408132814
10373
2593.25
=============
So I am taking I need to add 150fps to approach the standard factory ADI load and its accuracy of < 1MOA, so I need some BM2.
I will have a look at the ES next.
These are Fed205MAR primers for the 69grain and Fed210 for the 303brit. I have some 210M I will try these to see if they improve the SD at all.
I would also say the wincester cases are more consistant for weight then the 1943 cases.
What would be interesting is whether SD can give you an indication of a wearing barrel. The stag barrel is brand new while the Pattern 1914 is 100 years old. yet more things to experiment with.
:thumbsup:
SD will give a better idea of how consistent/repeatable your ammo is. ES just gives the highest and lowest velocities.
Consider these two imaginary 5 shot strings
3000, 3000, 3000, 3000, 3020
3000, 3005, 3010, 3015, 3020
Both have the same ES, but the first one will have a lower SD
The Q would be is there a noticable improvement in grouping between the two? if not then ES maybe the better measure, if yes then the SD is surely? Next time I intend to take an old digital camera up and record the shots as they arrive, just have to hope the battery is still OK and no idiot shoots it...and that includes me, LOL the nasty is the shrapnel when others are wacking steel plates.
If I had to choose between those two hyperthetical strings to progress fwd with my load development, keeping in mind that such small samples are statistically suss, I would choose the first one and try to explain why 1 shot was out from the others. Could be many reasons. Groups at that stage could be less than perfect despite low ES and favourable SD. Time to frig with seating depth. Yeh, seeing your shot fall at say 500yds (must move out to at least that range once happyish at 100yds, but probably 250 for hunting type conditions) needs to be recorded in order against your brass fired. Also keeping your brass once fired in your box in order. Have seen guys trying to do serious long range load development arrive on the mound and tip a whole lot of loaded ammo out of a plastic bag on to the grass! And once fired they are all returned to the bag, assuming none got lost. Seems they are a few of use building camera systems right now similar to 7mmsaum's.Quote:
Originally Posted by steven
OK, another of my "$0.02c".
I am relatively new to shooting, hunting and reloading but however i don't have much experience i do "research" A LOT.
In my understand, and what i think i learn with my research regards SD and ES are:
SD - is "somehow in MY understand" the "measurement or estimation" of how much the bullet vary from a "straight line" as it exit the muzzle of your rifle or pistol, saying it, i can not confirm if it is real or not or how it is measured during the process, but, as we all(or many of us here) talk about "concentricity" and "bullet alignment" during the seating process i think it is how they "ballisticians" "calculate or estimate how "far" the bullet path is from a "straight" line, if the bullet is seated not "centred" enough the path will be "unknown" with the POI varying with a higher "off alignment". So, if you shooting at long ranges it will affect your accuracy.
ES - is in my understand the measurement of "how consistent" your bullet velocity will be so it will "hit" closest to the "centre" or point of aim. If any of you guys watch Brian Litz videos i am sure you will find some more "technical" info there and with a lot more "quality" than my own "findings". the lesser is the speed variation the less chance the projectile will hit away of the centre.
Well, i think i wrote too much so i will stop here with a quick "conclusion". The smaller are the numbers achieved in SD and ES the better it will be(or should be), however other factors can and will contribute to the final "accuracy" with examples such, bullet seating depth, max velocity, case capacity, etc, etc, etc. so, if you really want to compete in F-Class and its variables or bench rest match you may need to "study" in depth all of these variables.
I hope it help a bit and i apologise if i wrote some or a lot of "BS" but as i said, it is only my understand. If someone here can clarify more or correct me please do it.
Thank you for your time.
Mac
SD is standard deviation, a mathematical calculation of how far away from the mean the results are. (I think) 1 standard deviation is +/- 34.1% away from the mean. ie 66.2% of results are within +/- 1 SD of the mean.
OK, just another little "fixing" trying to make easy to understand.
SD can be how far the projectile will deviate from the POA because the speed variation. the higher is the ES the higher will be the SD to the POA. A projectile flying at 2900ft//s will "theoretically" hit a target at 800 metres "bulls eye", if the next projectile has a estimated velocity of 2800ft/s it will hit the target at maybe 2" low. from this "example" you/we can try to figure out what we trying to understand regards "SD and ES", the more consistency we have the more "accurate" it will be, or should be.
Sorry again for more "crap".
Mac
Hi, I've tried to put down an explanation of SD and ES. http://www.nzhuntingandshooting.co.n...t-es-sd-22402/
Hope it helps a bit.
The effect of a given ES can be found for both drop and susceptibility to drift from wind by feeding the two extreme values into a exterior ballistics program and comparing the outputs at the range of interest. As to a link between accuracy and variation in muzzle velocity I agree with the other replies and treat them as independent and the effects as additive.
I'm with you on this .Quote:
Originally Posted by Kiwi Greg
the load in the pic shot crap and the load I went with has an ES of 23fps
Attachment 40265
68.2%, but yes.Quote:
Originally Posted by stug
SD being the stuff in dark blue (the most common distribution), with ES being the shots at extreme ends of the scale:
Attachment 40266
Yes, all very interesting but overly complicated.
A fair summary might be:
SD- How consistent are my velocities on average?
ES- What are the worst case velocity variations?
(PS. I used to tutor in stats)
