LOWERING ES and SD - Need advice achieving consistency

[heavyhorns]

I have only been reloading a few months but feel like I am making progress and really enjoy it. Loading for a 223 tikka(lapua brass and 8208) and 7prc(adg brass and 4831sc). Shoot quite a bit at 500 yards and I am happy with groups. I have loaded around 500 rounds so far. Using a garmin xero chrono, I have only been able to achieve single digit SD's one time that had ES's in the teens. I have no idea how I did that and haven't been able to repeat it. I am using a RCBS chargemaster for powder, Forster Co ax, redding s series dies w neck bushings. I have not used expander mandrels. I have not started annealing yet. Curious what you guys have for advice as I try to achieve lower sd's and es's. Upgrade scale? Anneal? Expander mandrel? Anything else I am not thinking about? Thanks for helping out a new guy.

 

[flyfisher117]

Chasing smaller SD/ES can get expensive quick. I started down a rabbit hole chasing smaller and smaller. For what I do the juice wasn’t worth the squeeze.

A better scale is probably one of the best upgrades. A&D FX 120i is my next step. Some day.

You could experiment with a torch and socket annealing and just see if you get any changes. I went from salt bath annealing to torch machine annealing. Should have just went induction but again..$$$

Have you tried changing primer brands or bumping up to “match” primers? That would be a relatively cheap experiment.

 

[MCS]

I have only been reloading a few months but feel like I am making progress and really enjoy it. Loading for a 223 tikka(lapua brass and 8208) and 7prc(adg brass and 4831sc). Shoot quite a bit at 500 yards and I am happy with groups. I have loaded around 500 rounds so far. Using a garmin xero chrono, I have only been able to achieve single digit SD's one time that had ES's in the teens. I have no idea how I did that and haven't been able to repeat it. I am using a RCBS chargemaster for powder, Forster Co ax, redding s series dies w neck bushings. I have not used expander mandrels. I have not started annealing yet. Curious what you guys have for advice as I try to achieve lower sd's and es's. Upgrade scale? Anneal? Expander mandrel? Anything else I am not thinking about? Thanks for helping out a new guy.

My ES went up when I use the charge master. I don't believe that the scale is very accurate on them. My ES is way better when I use the lyman. I friend I shoot with also has poor ES and he uses the charge master.

 

[slim jenkins]

I can’t say definitively but I believe case fill is important part of the equation. I can and do get single digit S/Ds with new brass in at least two chamberings that cases are pushing 100% fill. I am using a V4 with FX-120 yet still struggle with other rifles to get low SDs. The AMP annealer has brought those numbers down.

Another possible cause can be if the bearing surface of the bullet is coming in contact with the donut formed at the neck/shoulder junction.

Edit to add that my data is from a minimum of 10 shots. Most are 20 shots or more and have Xero data screen shots that I can post for the skeptics.

 

[heavyhorns]

Chasing smaller SD/ES can get expensive quick. I started down a rabbit hole chasing smaller and smaller. For what I do the juice wasn’t worth the squeeze.

A better scale is probably one of the best upgrades. A&D FX 120i is my next step. Some day.

You could experiment with a torch and socket annealing and just see if you get any changes. I went from salt bath annealing to torch machine annealing. Should have just went induction but again..$$$

Have you tried changing primer brands or bumping up to “match” primers? That would be a relatively cheap experiment.

No doubt on the expensive! I am using 215m on the 7prc. A&D is a hard one to choke down at the moment.

 

[wind gypsy]

I've never achieved particularly good SD on 223 with a significant sample size. Some F-class guys might have tuned things with 10 special steps but IMO you're wasting your time chasing it. You'll get bent by the wind long before it matters as long as it's not atrocious. Teens is good enough for that cartridge for what most anyone does.

Hot tip - a whole bunch of people claiming super low SD/ES on the internet are spouting single small shot count sample sizes and not actual repeatable #s over significant sample sizes. Some cartridges just make it easy. Like i almost have to try to get double digit SDs with 6.5x47 but most larger cartridges seem to most commonly be in 9-14 ish range for SD with large enough sample sizes. I hear the BR variants are the same as the x47 in that regard.

If you must focus on something, Consistent powder charges, neck tension, and seating pressure is probably where id look.

If your primary interest is load experimenting and tinkering, by all means dive into the rabbit holes. If you want to get better at hitting stuff, get to good enough and spend more time shooting in a manner that makes you better at shooting (I.E. not endless load dev from the most stable setup possible).

 

[hoooogan]

Aside from being more consistent in the loading process, keep in mind that velocity does not scale in a straight linear line. There are waves or "nodes". If your charge is sitting on a steep up or down swing, you can chase ES/SD forever but the charge is not stable. You want your charge to be on a flat area where a slight variation in either direction doesn't dramatically change velocity. I have recorded many sub 1.5 SD's but further along the load ladder, it can spike to 15-20 SD. Same process, same components. You can try to tune accuracy with bullet jump after you find a stable node.

Stole this image from Google:
This example shows 39.5gr is in the middle of an extremely flat velocity node. +/- 0.1gr has virtually no velocity change. That's around where you want to be. You don't want to be at 40.1gr on the steep rise where +/- 0.1gr has a ~30fps difference. FWIW, I've found these nodes and had repeatable single digit SD's with my first cheap lee press, dies and $15 pocket scale.

EDIT: want to clarify that stable ES/SD does not mean good accuracy. But if ES/SD is what you are chasing, that's a start.

 

[Wrench]

Single digits and teens.....what problems are you hoping to solve? The accuracy of the chronograph is literally the equivalent of the spread.


Just shoot it.

 

[streamerfish]

If your happy with your groups, then I would completely forget the terms SD and ES.

Actually I would forget the terms regardless.

Your SD is probably gonna have to be somewhere in the 50fps or more range to see the difference at 500yards...and even then, its probably going to take a bunch of high volume (maybe 20+shot) groups to see it.

And thats assuming your rifle system is accurate enough for it not to be swallowed up in the noise, and your a good enough shooter for it to appear.

We all have things we like to geek out on.

But this is one thats not going to get you anywhere.

 

[Slugz]

Big rabbit hole you could go down.

Generally speaking you are making really good rounds if you are doing the below points.

-Get the best brass you can
-Match grade primers
-Consistent primer depth
-Accurate scale to the hundreths
-Match grade bullet seater

After the above you could go down the consistent neck tension route with several paths and philosophies.

 

[flyfisher117]

I've never achieved particularly good SD on 223 with a significant sample size. Some F-class guys might have tuned things with 10 special steps but IMO you're wasting your time chasing it. You'll get bent by the wind long before it matters as long as it's not atrocious. Teens is good enough for that cartridge for what most anyone does.

Hot tip - a whole bunch of people claiming super low SD/ES on the internet are spouting single small shot count sample sizes and not actual repeatable #s over significant sample sizes. Some cartridges just make it easy. Like i almost have to try to get double digit SDs with 6.5x47 but most larger cartridges seem to most commonly be in 9-14 ish range for SD with large enough sample sizes. I hear the BR variants are the same as the x47 in that regard.

If you must focus on something, Consistent powder charges, neck tension, and seating pressure is probably where id look.

If your primary interest is load experimenting and tinkering, by all means dive into the rabbit holes. If you want to get better at hitting stuff, get to good enough and spend more time shooting in a manner that makes you better at shooting (I.E. not endless load dev from the most stable setup possible).

All of this. I shot a 0 SD/ES 3 round volley a few weeks ago. The next 7 shots bumped it up to nearly 20 lol.

Also attached is two different bench sessions. Same rifle. Same batch of ammo. Same everything other than day and weather.

I spent too much time and money going down the node and SD rabbit holes. It was such a waste in hindsight. I was chasing these mythical unicorns everyone claims in the internet. Then I realized it’s just their 1-3 rd sample bias they were reporting.

 

[Slugz]

All of this. I shot a 0 SD/ES 3 round volley a few weeks ago. The next 7 shots bumped it up to nearly 20 lol.

Also attached is two different bench sessions. Same rifle. Same batch of ammo. Same everything other than day and weather.

I spent too much time and money going down the node and SD rabbit holes. It was such a waste in hindsight. I was chasing these mythical unicorns everyone claims in the internet. Then I realized it’s just their 1-3 rd sample bias they were reporting.

Spot on

 

[43.6N]

I have only been reloading a few months but feel like I am making progress and really enjoy it. Loading for a 223 tikka(lapua brass and 8208) and 7prc(adg brass and 4831sc). Shoot quite a bit at 500 yards and I am happy with groups. I have loaded around 500 rounds so far. Using a garmin xero chrono, I have only been able to achieve single digit SD's one time that had ES's in the teens. I have no idea how I did that and haven't been able to repeat it. I am using a RCBS chargemaster for powder, Forster Co ax, redding s series dies w neck bushings. I have not used expander mandrels. I have not started annealing yet. Curious what you guys have for advice as I try to achieve lower sd's and es's. Upgrade scale? Anneal? Expander mandrel? Anything else I am not thinking about? Thanks for helping out a new guy.

A couple of thoughts about ES and SD.

First is that we all want the absolute best, most high quality ammo that we can make. It’s a process, and in general we think, if my numbers are tighter I must be “doing it better.” To try and seek perfection at the expense of good is to be human.

Next is that our ability to measure ES and SD only really became a thing with consumer grade Doppler chronographs becoming widely available. Sure the optical and barrel mounted ones could provide the info, but were cumbersome enough that nobody was collecting high enough volumes to really give accurate statistical distributions. They also struggled with sensitivity.

We used to use water marks and drop validation at distance to true our velocity. This gave good ballistic data, but not so much info on how consistent the reloading processes were.

I bring this up because the athlon and Garmin chronos have a sampling error that needs to be accounted for. Athlon lists it as +/- 0.1%
For a 2700fps load, that’s an ES of 5.4.

So anybody reporting single digit ES is approaching the minimum sensitivity of the chronograph. Basically all other noise and artifact has been eliminated, and we are down to the limits of our equipment.

Finally, most of the ES and SD reports that I’ve seen are usually only 3 shot samples. This will lead to artificially low numbers.

Now there absolutely are true single digit loads out there. But the majority of “single digit” groups are actually ES of 25 and SD of 15’s when sampled over 20 rounds or more. Which by the way is very good.

 

[Ramem7mm]

This could be a giant rabbit hole especially for a new reloader, however once you start to get it figured out its rewarding and fun.

First off what is your goal for these rifles to need to achieve single digit numbers?

Second what is the ES you are getting and not happy with? Anywhere in the 20-30 FPS is generally very acceptable for hunting.

Provide more info on the cartridge you have developed for both rifles and if they are custom or factory and twist rates just to provide insight.

Bullet weights and powders combinations can vary so if your using the wrong combo then you might not be able to achieve your goal.

 

[HairyScandinavian]

Aside from being more consistent in the loading process, keep in mind that velocity does not scale in a straight linear line. There are waves or "nodes". If your charge is sitting on a steep up or down swing, you can chase ES/SD forever but the charge is not stable. You want your charge to be on a flat area where a slight variation in either direction doesn't dramatically change velocity. I have recorded many sub 1.5 SD's but further along the load ladder, it can spike to 15-20 SD. Same process, same components. You can try to tune accuracy with bullet jump after you find a stable node.

Stole this image from Google:
This example shows 39.5gr is in the middle of an extremely flat velocity node. +/- 0.1gr has virtually no velocity change. That's around where you want to be. You don't want to be at 40.1gr on the steep rise where +/- 0.1gr has a ~30fps difference. FWIW, I've found these nodes and had repeatable single digit SD's with my first cheap lee press, dies and $15 pocket scale.

EDIT: want to clarify that stable ES/SD does not mean good accuracy. But if ES/SD is what you are chasing, that's a start.
View attachment 1039060

Thank you for posting that, as a new reloader that makes it easy to comprehend exactly what you're saying.

I shot some loads yesterday and my best 5 shot group (.46") has some stupid ES of 70+ and SD in the mid 20's, but I have a 5 shot with another powder that had an ES of 6 and SD 2 something that only shot .7 or so. I'm not going to chase the numbers but the ES of 70+ is enough to throw off a calculator and dope LOL. Now the question is do I try to go up or down on the charge weight to find the flat spot... probably can't go up much due to pressure.

 

[streamerfish]

btw....I meant to put this as well...

If your anywhere near single digit SD, and your happy with your groups. Then yeah, I would definitely say that your doing a great job reloading. Good work.

 

[majg1234]

As others have said it can be an expensive rabbit hole,before I started using a chrono I loaded for smallist groups over 5-10 shot strings I had many 1/2-3/4 -1 MOA groups during that period of my shooting
Then along came the Chrono,I chased some of the same rabbits you are looking at and guess what? groups didn't improve all that much (a little granted).So after that I reverted back to my old method of getting good groups (I'm a hunter). Can't hit it can't eat it LOL.Now my primary use of the chrono is to find speeds of new loads and if the ES/SD's are good ...OK,but if the groups are good even better!

 

[streamerfish]

Thank you for posting that, as a new reloader that makes it easy to comprehend exactly what you're saying.

I shot some loads yesterday and my best 5 shot group (.46") has some stupid ES of 70+ and SD in the mid 20's, but I have a 5 shot with another powder that had an ES of 6 and SD 2 something that only shot .7 or so. I'm not going to chase the numbers but the ES of 70+ is enough to throw off a calculator and dope LOL. Now the question is do I try to go up or down on the charge weight to find the flat spot... probably can't go up much due to pressure.

I would be leery of trying to chase so called velocity nodes...

While in theory it may be possible that somewhere within the pressure profile of a charge ladder there may be a spot where the grid line "may" flatten out slightly, and I mean very slightly at best.......I have yet to see anyone be able to prove it out once you get into statistically relevant data sets. Every large scale set of testing in controlled environments by professionals have debunked or not been able to show that it exists.

Its just more small data set white noise.