Needing Opinions on ES

[savageshooter86]

Been shooting over the Magnetospeed to get some data. BUT I am getting something strange and not sure what might be causing this to happen. In 5 shot groups I am getting 1 strange outlier shot that is making my ES bigger. I weigh all charges to 0.02 gr and all brass have same # of firings. OAL is measured on each round to the ogive. Bullets were sorted by bearing surface. Any helpful hints on what may be causing this??

308win 168Hybrid Varget KVB7 Lapua Brass

Here is my data

11/23/2013 62F 86% 30.14

45.9gr 3.205" 45.9gr 3.180"
1.2917 1.2896
2.2901 2.2888
3.2908 3.2910
4.2896 4.2905
5.2886 5.2903
AVG-2901 AVG-2900
ES-31 ES-22



12/4/2013 80F 56% 30.00

45.9gr 3.180" 45.9gr 3.180" 45.9gr 3.205"
1.2866 1.2910 1.2908
2.2905 2.2905 2.2896
3.2917 3.2893 3.2886
4.2903 4.2885 4.2912

AVG-2897 AVG-2898 AVG-2900
ES-51 ES-25 ES-26

 

[ShootDots]

You could try this: Keep the Magnetospeed on your rifle and get an additional chrono. Set the chrono so it passes thru the Magnestospeed AND thru the other chrono and see exactly what is going on.. I get those "way out there" readings too on my PACT Professional>>>BUT that seems to be more often on a bright morning when the angle of the sun is right UNDER the skyscreens... I bet if you set it up that way, you would be surprised at what may show up in the way of readings..

 

[savageshooter86]

this is the only reliable chrony I have access to. Just strange how all the other 17 shots were very close and repeated but in each group I had 1 reading(each time it was almost the same velocity reading that was off 2886). Just thought that was odd

 

[savageshooter86]

so if that is true what steps would I do to tighten ES up? Assuming it is something I can do to help

 

[kelbro]

Do you anneal?

 

[savageshooter86]

I did after 3 firings. These have been fired 1x since then

 

[navyrad8r]

drew,
would culling those cases from the odd shots keep the ES better? just a thought...along the lines of annealing like kelbro said but since you did, maybe those cases are the culprits? ???
cheers,
doc

 

[savageshooter86]

I had read that somewhere before about culling cases but had forgot about it until you mentioned it. Not sure but only one way to find out

 

[Lapua40X]

If you've already confirmed this adjustment then disregard my comment.
But it's critically important to make the muzzle is 0.25 to 3.0 inches down range from the front of the "V" block so it overhangs the blast zone of the bayo unit. In my experience, that's the most often missed requirement in attaching the chrono to the rifle. If you're over the blast zone by .25 inches, see how 1.5 inches works for you.
Frankly, this ES registers a SD of 9 which isn't all that bad IMO.

45.9gr 3.180"
2910
2903
2905
2896
2888
AVG-2900
ES-22

 

[savageshooter86]

I do put muzzle about 1.5" into blast zone. I will try to check at 350 yards again and see what velocity I get vs POI on target. I have considered a tuner. I guess my ES aren't horrible being in the mid to low 20s. This load so far for me at 100 and 200 have shot right at 0.5" or less.


Group 1 I shot at 350 yds the other day that had the 3.180" and 2897 fps and ES-51.

These two groups(1 marked with X over the holes and the other with a dot under the hole) were the 3.205" loads that had 2898 and 2900 fps and one had ES of 25 and the other 26


Now I should have been plotting the shots but I didn't. Stupid me. That could have told me if the "out of the group" shots were somehow the low velocity shots or not

 

[BradY]

Is this your most accurate load? Typically match bullets seem to run in a couple of accuracy nodes, one being around 2830fps, the other in the 2900's. If you increase the load or decrease it to suit those velocities, what is your accuracy and your ES like? Your rifle might be a candidate for a tuner if you get better numbers but not quite as good groups at a different average velocity.

 

[jcampbellsmith]

I think your statistical analysis is flawed. I think you are cherry picking the numbers. Try shooting 20 rounds of one specific load and see what SD you get then. ES is for the birds.

Regards

JCS

 

[savageshooter86]

This is the first time I had shot with a reliable(from all reviews and info I have heard) Magnetospeed. And know that 5 shots don't tell you everything you need to know. I will at one point near future shoot a 20 shot string to see what numbers I am getting. And will be sure to plot each shot to match the velocity reading. I am new to this chronograph thing

 

[normmatzen]

Well, I just got a press with a seating force gauge on it and have been monitoring actual seating force.
I have found that with a group of loads that have very similar seating force I get very low ES values and with groups with various seating forces I get larger Es values.
After shooting 5 shot groups at 600 yd and 1000 yd in practice, my groups with low ES are remarkably tighter than those with large ES values. I, too, load to within 0.02gn with a VERY accurate force restoration lab balance.

 

[jcampbellsmith]

I think your statistical analysis is flawed. I think you are cherry picking the numbers. Try shooting 20 rounds of one specific load and see what SD you get then. ES is for the birds.

I view it the other way around, and thrive on the facts (ES), not on a statistic that is only a probability (SD) that takes at least 20-shots to get a higher percentage of probability certainty.
While I will agree SD has its place (when a load is in the final stages of development or completed), but it takes a whole lot of barrel life and ammo expense to do SD justice. Any thing under 5-shots is very poor probability, and even 10 samples won't cut the mustard for a good deviation statistic, and is basically meaningless.

If a chronograph and its setup does not simulate the POI on target at least 75% of the time, the data is in error and all ES, SD, and Averages are as well. Personally I won't settle for a setup that does not yield at least 85% certainty.

My 2-cents
Donovan

Fact - ES compares the velocities of two shots, the fastest and the slowest, it says nothing about the intermediate velocities or their distribution.

Regards

JCS

 

[savageshooter86]

Like you said ES shows difference in high to low velocity. If you keep that difference low, at long range in theory your vertical will be tight. Then your shots in between would fall within that vertical between the ES right? And wouldn't you have a low SD if you had a low ES?

 

[jcampbellsmith]

Like you said ES shows difference in high to low velocity. If you keep that difference low, at long range in theory your vertical will be tight. Then your shots in between would fall within that vertical between the ES right? And wouldn't you have a low SD if you had a low ES?

Exactly !.!.!

No. You're kidding yourself. ES is a poor proxy for Standard Deviation. ES tells you nothing about the intermediate velocities. SD does. Just because ES is an easy number to produce, doesn't actually make it very useful.

Regards

JCS

 

[savageshooter86]

 

[Keith Glasscock]

It's got to be the weather...

 

[BoydAllen]

Let me see, in long range competitions for group, the farthest two shots determine the group size, and the group constitutes a sample that is too small to base statistically valid conclusions on. If we were to compare loads, for any distance, based on ideal sample sizes, what percentage of the competitive accuracy life of a rather expensive barrel would be sacrificed? Does that load need to be requalified for different ambient conditions? Of course this is all rhetorical, but it is why shooters make decisions on small statistically invalid samples all the time. They cannot afford to do otherwise. Generally, I have found that when I follow good reloading practices, that if there is going to be a less than ideal outcome, that it shows up in a relatively small number of shots. Friends that shoot at much longer ranges, have to jump through more hoops to reload competitively for their sport, but I think that the same may be said. If they have good rifles, and their charge weights are very closely measured, and their bullet seating forces are consistent, then what they see, on a good test day, with a relatively small sample, is valid for their purposes, and it is their opinion, based what shows up on the target that matters. The chronograph can be happy with a load, that the barrel is not, so the target must have the final word. In short range, velocity differences are not much of a guide to accuracy. You can have a load that looks quite mediocre on the chronograph, and still win, but it had better not be out of tune.