Consistent ES and SD

[Capt RB]

Many times a new pistol shooter will have feeding problems due to a poor and inconsistent grip. In a similar fashion a rifle shooter can have inconsistent recoil management causing larger shot to shot variations One way to find out would to free recoil the rifle in bagsanotehr would to have a good shooter shoot it prone then shoot it from a bench . This has shown variances in both load speed and deviations. If the rifles have shot 1 or 2 .250 groups but oens up in similar DA conditions with same lot components it's you.

 

[Capt RB]

This barrel is finally starting to shoot after 125rnds. This load is a 190smk @2910. SD is running 1.7fps and ES is 8 for 10rounds. The sights are adjusted .2 mills left so I don't shoot out the point on the diamond First 2 are cold bore and confirmation then .3 down and the 5 in the group. I then went to 2 and 300.to confirm it will shoot and put it away. If you can see the bottom diamond it has 2 touching and one about an inch and 1/2 below. That is a problem child 308 rem700 I've spent way too much time on. That rifle has never shot well 410rnds to date. It will have a new barrel before it goes back to the range.

 

[baldhunter]

This barrel is finally starting to shoot after 125rnds. This load is a 190smk @2910. SD is running 1.7fps and ES is 8 for 10rounds. The sights are adjusted .2 mills left so I don't shoot out the point on the diamond First 2 are cold bore and confirmation then .3 down and the 5 in the group. I then went to 2 and 300.to confirm it will shoot and put it away. If you can see the bottom diamond it has 2 touching and one about an inch and 1/2 below. That is a problem child 308 rem700 I've spent way too much time on. That rifle has never shot well 410rnds to date. It will have a new barrel before it goes back to the range.

This is what my PacNor barrel looks like.Your barrel looks like a dirty file.I'd imagine it would affect your velocity spread as it loads up with copper.

 

[DoneNOut]

This barrel is finally starting to shoot after 125rnds. This load is a 190smk @2910. SD is running 1.7fps and ES is 8 for 10rounds. The sights are adjusted .2 mills left so I don't shoot out the point on the diamond First 2 are cold bore and confirmation then .3 down and the 5 in the group. I then went to 2 and 300.to confirm it will shoot and put it away. If you can see the bottom diamond it has 2 touching and one about an inch and 1/2 below. That is a problem child 308 rem700 I've spent way too much time on. That rifle has never shot well 410rnds to date. It will have a new barrel before it goes back to the range.

Yup, that is a typical Savage barrel. They will laser beam if one knows to manage the copper.

 

[DoneNOut]

This is what my PacNor barrel looks like.Your barrel looks like a dirty file.I'd imagine it would affect your velocity spread as it loads up with copper.

That is a pretty one. I have two Benchmarks, and two CBIs just recently. They are pretty too!

 

[BrentM]

Some people believe heavily in primer testing. I run Federal 210M after having a lot of issues with CCI. That being said, anneal, neck lube, and consistency all the aspects you mentioned are usually good recipes for lower es and sd. One thing that skews those numbers is sample data. The more data you have the larger the es and sd usually become. More often than not most people use a very small sample data set to claim super low numbers. If you follow Litz, he specifically addresses this issue and claims single digit es and sd are harder to get then people are willing to admit. I have taken a load that proved to be in the extremely low sd range on a small sample and then ran the labradar every time I practiced with that rifle. The sample group grew to roughly 100 rounds and my sd increased. The data set went from 1.5 SD and 8 ES to 10 sd and 20 es. Looking at a bell curve it was and is quite exceptional and, according to Litz, that is right where a target rifle settles in, mine are hunters. So, I am quite happy with large samples and sd's in the low 10's. But that is just me; I am not willing to brass sort, complete WASTE of time, bullet bearing surface sort, and neck turn. I anneal, trim, mandrel expand, and play with shoulder set back. Some like .002 and some like .003-004. I settle in on .0025 for both neck tension and shoulder set back these days and it has been working fine for me.

 

[DoneNOut]

I get the lowest SD with Hammer bullets. No lube, .004" neck tension and a crimp. 4-8SD the norm. I lube the necks on the Bergers and .001" neck tension and its a crap show. Bug holes though...

 

[SmokinCrow]

What i dont understand is when i am shooting an OCW Test and the load with the smalles ES and SD shoots the worst. And another load with like a 15-20 SD shoots under 1/2"

Something to think about here is also how the statistics work. How many shots are you taking to calculate your sd/es? 5 shot groups aren't really enough to get true valid data. To get the most accurate information you need 30 shots for the sd to have sufficient data to be true and understand the bell curve of the sd. 66% of shots will fall within 1 sd of the average. 33% will fall within 2 sd of the mean. So you may not be seeing truth in any given group. That good sd/es that shoots bad could very well be one of the extremes that fall on the outliers and be in the far end of the 2nd sd of the average. Next several groups with same load could come in between 1/2-3/4 moa average.

Hornady has a podcast where they discuss the statistics and group sizes. Having taken stats in college I didn't put it together until I heard this podcast. I'd been chasing my tail trying to figure out why I always seemed to be chasing my tail with groups. I wasn't collecting enough data. I won't say the Hornady guys are the foremost experts and must be gospel truth. They don't say they are either. They say they are sharing what they have come to find in their testing and statistically makes sense. They say if something works for you great. They aren't trying to poopoo on other methods. They are sharing what they find with all their testing. Well worth a listen and very helpful. I asked them about sd/es and they said generally if there is an issue there neck tension is most common culprit. Also dispersion can increase with higher powder charge. Which makes sense when people talk about nodes and they find an upper node and a lower node with velocity and generally lower node tends to shoot better.

Good luck. Aim Small, Miss Small

 

[willfrye027]

What is your ultimate goal? Are you shooting ELR?

Some of the F class guys are going away from ES/SD completely. They are finding that it does not necessarily correlate to what they're seeing on target down range.

Pick your tightest shooting loads and shoot them at the farthest distance you plan to. I bet your vertical dispersion will be LESS than you think it is. The whole ES contributing to higher vertical dispersion is not necessarily true; I won't pretend to understand the physics but it's well documented.

 

[DoneNOut]

What is your ultimate goal? Are you shooting ELR?

Some of the F class guys are going away from ES/SD completely. They are finding that it does not necessarily correlate to what they're seeing on target down range.

Pick your tightest shooting loads and shoot them at the farthest distance you plan to. I bet your vertical dispersion will be LESS than you think it is. The whole ES contributing to higher vertical dispersion is not necessarily true; I won't pretend to understand the physics but it's well documented.

I was told the last super duper 1000yd match was won with a load that had SD of 40fps...

 

[Pudgy]

With great groups like that I wouldn't worry too much about it. For me the larger the case capacity the harder it is to get low SD ES numbers. My sizing process similar to yours however i like to use only Match and Magnum Match small and large rifle primers. I anneal first, pin wash, and just recently started coating the inside of my case necks with NEOLUBE#2 (graphite lube in a quick dry solvent). I was just looking over my notes from my last range trip to work up a new hog/ Coyote load for my 6.5 Grendel. Anyway I ladder tested 8208XBR, CFE223, 2520, and LeverEvolution. Of all those strings, I only had 2 strings with an SD higher than 9 and both were using the LeverEvo powder. Those SDs were 10 and 12 and the groups were horrible. I'd like to say the neolube helped but I'd have to do more testing with and without to be sure. Match primers can Definitely help.

I usually dont respond to these types of questions as there tend to be lots of conflicting answers, however, i have test over 1,000 rounds in the last 4 months. There is more to the subject then I can write here, so here briefly is my observation.

Low ES/SD is about consistent ignition Percentage of case fill doesn't impact ignition. Doesn't impact es-Sd

Use high end brass eliminates a lot of issues.
Sorting brass and primers has little to no impact on ES/SD
Anneal-trim every time, (while I mandrel, have not noted impact ES/SD
Bullet of consistent weight & bearing surface
Measure powder to .02 (V4 or SuoerTrickler make this easy)
Find right powder - primer combo.
For PRC changing from fed 215 to 210 primer SD when from 26 to 4 over 10 shot strings

with PRC find a node at least .4 grains wide with little velocity change.

Hope this helps and doesn't add to the confusion.

 

[RockyMtnUT]

I might have missed it but sort brass is #1 for me.
I generally end up with single digit es and sd. I don't care if its Lapua, Peterson, ADG etc I find 20-30 that are within a .1 or .2 of each other and use that batch.
When I'm done the whole group of cartridge's with powder, brass, bullet all weighs .1-.2 grains of each other.

Along that process I keep neck tension as equal to each other as possible.
There are so many variables. But keep it simple and consistent.
The comment about "sorting brass and little to do with it" is 100.54% opposite of my way of thinking.
You start with good foundation to build the cartridge off of. Consistency is key to all this. I can do this and do that, and many ways will work. Garbage in is garbage out.

 

[Pudgy]

Don't know how to edit post but would like to add. Generally (not always) when I see low SD/ES and wide groups, I am at or over pressure. Usually dropping couple grains fixes the issue.

 

[Pudgy]

Curious if you sort after fireforming/trimming or before?
Have you marked some of the outliers and tested them against the 30 to see if there was an actual difference?