ES too high

[918v]

That's a good thought, particularly if he's seating the bullet deep enough where the bearing surface contacts that donut area. There can be enough variance in the bullet's specs where sometimes it touches and sometimes it doesn't when one is just close to it. Though in the OP, he did mention he runs a mandrel through the neck, which will mitigate that issue; even more so if he's annealing his brass properly.

I was thinking that if the donut gets too fat the bullet will get pinched when the round is chambered. The pinch will cause pressure spikes and big ES.

 

[straightshooter1]

I was thinking that if the donut gets too fat the bullet will get pinched when the round is chambered. The pinch will cause pressure spikes and big ES.

Yeah, whether it's the donut or the carbon ring causing a pinch, it will cause pressure spikes. But, unless the round is seated long enough for the bullet to make contact with the lands, I don't know why chambering would cause the bullet to move into the donut . . . ??? I suppose if the neck tension wasn't sufficient, recoil might move the bullet to touch the donut to some extent, but then, that would mean there more than just the donut at play that would cause such an ES.

 

[markl323]

Sometimes when you run the mandrel through the neck too aggressively it puts a slight flare at the mouth of the case. The neck is resisting penetration and flares the end of the neck slightly.

yes. I have been going through the mandrel step very slowly! same with shoulder bumping and bullet seating.

teek your load try higher or lower , switch up primers a few of my loads run single digit 5's to double digit 40's or more just by switching primers especially when I use winchester primers thought it all still shoots fine group wise to 600 yards .

I have tried the followings and have not been to get rid of groups with high ES:
H4350
Alpha SRP + CCI 400

RL 16
Alpha SRP with CCI 450 ad BR4
Lapua LRP with CCI 250

I'm going to try a new primer Federal 205Match next trip to the range. Plus I'll do an OCW test as well. Plus I have the Annie annealer coming LOL. I'm so committed now.

 

[Rio Precision Gunworks]

Something always keep in mind is exactly how SD and ES work statistically. Most aren't aware what the actual SD numbers their chrono spits out actually mean.

To get the correct data, you'll need to extrapolate the SD using confidence intervals and the amount of shots fired. 95% is the most common interval used.

So, for example, if you fire a 10 shot string, and have an SD of 8......using a 95% confidence interval, your true SD is somewhere between 5.5 and 14.5fps. Meaning if you were to shoot enough rounds to be very sure your SD is the true SD of the ammo, it would be somewhere between those two, 95% of the time.


Now, SD itself is a distribution. Meaning 68% of your shots will be within one standard deviation. If you have an 8sd, 68% of your shots will have an ES of 16 (8 each way).

95% of your shots will be within two standard deviations. Which means if you shot 100 rounds, 95 of them would be inside an ES of 32fps (two SD of 8 each way.

99.7% of your shots will be within three standard deviations. We'll just round up to 100%.


Which means, if you have a true sd of 8, if you shoot 100 shots, you will have an extreme spread of 48fps.


If you only shoot a 10 shot group and get an SD of 8, with the confidence interval calculated, you could actually have an ES of up to 87fps.

 

[Rio Precision Gunworks]

If you have a true to life SD of 5, your ES is 30.

That should put a lot of this in perspective.



Most people would agree a true to life real 5fps SD is extremely good ammo. Some of the best ammo you could ever make.

And that ammo will still have an ES of 30fps.

 

[FredHammer]

Something always keep in mind is exactly how SD and ES work statistically. Most aren't aware what the actual SD numbers their chrono spits out actually mean.

To get the correct data, you'll need to extrapolate the SD using confidence intervals and the amount of shots fired. 95% is the most common interval used.

So, for example, if you fire a 10 shot string, and have an SD of 8......using a 95% confidence interval, your true SD is somewhere between 5.5 and 14.5fps. Meaning if you were to shoot enough rounds to be very sure your SD is the true SD of the ammo, it would be somewhere between those two, 95% of the time.


Now, SD itself is a distribution. Meaning 68% of your shots will be within one standard deviation. If you have an 8sd, 68% of your shots will have an ES of 16 (8 each way).

95% of your shots will be within two standard deviations. Which means if you shot 100 rounds, 95 of them would be inside an ES of 32fps (two SD of 8 each way.

99.7% of your shots will be within three standard deviations. We'll just round up to 100%.


Which means, if you have a true sd of 8, if you shoot 100 shots, you will have an extreme spread of 48fps.


If you only shoot a 10 shot group and get an SD of 8, with the confidence interval calculated, you could actually have an ES of up to 87fps.

I always looked at ES/SD like, "Big numbers no good, small numbers better, and single digit best".

 

[Rio Precision Gunworks]

I always looked at ES/SD like, "Big numbers no good, small numbers better, and single digit best".

SD really gives you all the info you need. Anytime you have an ES smaller of around 6 times your SD, all that means is that you haven't shot enough shots to get your real ES.

And ya, the smaller your SD, the better. Even when shooting very small sample sizes, the smaller your observed SD, the smaller the range of a 95% confidence will be.

For example, 10 shot strings

5sd = 3fps - 9fps

8sd = 5.5fps - 14.5fps


If your 10 shot string has a 5sd, you should not be worried if your ES is 54fps or less.


Meaning, if you take two different loads, shoot 10 of them across your chrono, both have a 5sd, but one has a 50es and the other has a 30es.....

You literally cannot say the 30es ammo is better as they are both inside the 95% confidence interval.




Not understanding this is a very big reason people chase their tale with ammo and chrono.

 

[Rio Precision Gunworks]

Every time I shot 10x 5-shots groups, there would be about 3 groups with ES over 30. sometimes they go into the 40s and 50s range.
I have tried Lee collet die, Redding full length sizing die, Forster Neck bushing + Full length size + mandrels (2/1k and 3/1k tension), Imperial Dry Wax. Did not see any difference.

The best 10 groups are typically with virgin brass where my average ES is 20 and SD is 10. but I still get 1-2 groups with ES of about 30.

My steps:
- De-prime
- Wet tumble
- Dry brass in oven for 1h at 200F
- Lube case and Neck bushing + length sizing
- Mandrel
- Dispense powder then seat bullet

6.5 CM
Berger 140 Hybrid and Berger 144 Hybrid
Alpha SRP
Relode 16 43gr
CCI 450, BR4

What else should I do?
Thanks for any help.

FYI, if your SD is 10......here is how your ES might play out. Based on 5 or 10 shot strings:

If you shoot a 5 shot string and get an SD of 10, your ES could be as high as 168fps

If you shoot a 10 shot string and get an SD of 10, your ES could be as high as 108fps


If your ammo is actually a true to life 10sd, your ES is 60. Just the way it works. So, being over 30 ES with a 10sd is extremely normal.


When you shoot a string and get an SD of 10, but your ES is 20......that 20es is not a valid observation. It is the product of not enough shots to make a proper observation of your ES, which is around 60(if your ammo is a true 10sd).

 

[FredHammer]

SD really gives you all the info you need. Anytime you have an ES smaller of around 6 times your SD, all that means is that you haven't shot enough shots to get your real ES.

And ya, the smaller your SD, the better. Even when shooting very small sample sizes, the smaller your observed SD, the smaller the range of a 95% confidence will be.

For example, 10 shot strings

5sd = 3fps - 9fps

8sd = 5.5fps - 14.5fps


If your 10 shot string has a 5sd, you should not be worried if your ES is 54fps or less.


Meaning, if you take two different loads, shoot 10 of them across your chrono, both have a 5sd, but one has a 50es and the other has a 30es.....

You literally cannot say the 30es ammo is better as they are both inside the 95% confidence interval.




Not understanding this is a very big reason people chase their tale with ammo and chrono.

If people don't take into consideration the ammo temp vs ambient temp, that will have them chasing tails too! Like, ammo stored in air conditioned house then hit the range in hotter temps. I'm letting my ammo acclimate for an hour before shooting. Tells a lot about powder temperature sensitivity!

 

[John Glidewell]

 

[FredHammer]

View attachment 8232398

Holy shit! Great job!

I have a 708 120gr Hammer load 50 shots with 9SD and thought I deserved a medal!

 

[secondofangle2]

View attachment 8232398

What load is that?

 

[John Glidewell]

6GT. 37.6 N555 with 110 Atip at .040

 

[SmileMaker]

300NM, H1000, Berger 208,
Lapua brass necks uniformed, wet tumbled, annealed, body sized, bushing neck sized (LE Wilson), arbor sized, neck dry lubed and loaded. Shame I missed the changing wind at 1000 yds.

 

[John Glidewell]

Record another 45 shots on that

 

[DeathBeforeDismount]

Anyone have a good load for 115 DTACS with Alpha brass and H4350?

I am getting 2850 with 109 Bergers and 36.1g H4350.

 

[markl323]

Hi all,

I need to give an update on this! Everyone has been very helpful.

Shortly making this thread, I had to take a break from shooting. When I got back to this hobby, i had to switch to a new rifle a factory 300 PRC.

Taking what i have learned from this thread and some help from a member at this site, I have made some major changes. Initially my average SD for the 300 PRC was about 15. But I have since reduced it down to about 7.7. Things that I noticed and fixed:

- The Lyman press was not good it frequently caused brass to get stuck. I think concentricity issue. I now use two Rock Chuckers. One for FLS and depriming and one for the mandrel.
- I now try 3 different powders and 3 different brands of primers. I think this gives the biggest improvements for me.
- I also annneal, full length size, trim cases, sort primers by weight, chamfer, deburr case mouths.
- Instead of wet tumble with SS I use an ultrasonic cleaner.
- I seat primers 0.002” crush.
- I also upgraded all my equipments to 21st centuries, AccuracyOne and L.E. Wilson.

My next step is neck turning and see if I get even better ES/SD. This has been quite a ride

 

[supercorndogs]

Reloading practices are religion. And just like religion, attacking someone else's practice is, well, pissing up a rope.

There is no "right way" to do it. People have to find what works for them.

I do find it humorous that one person says "Reloading is not hard, you just need to understand each process and how to do it effectively and efficiently to make good ammo." and then admits (in their very next post) that they had to change their process, and trim/chamfer as a last step (doesn't everybody?). Which means they really didn't understand the process, and had to learn what worked for them... LOL!

As for peening happening without pins...I've never seen that. But that is just my experience. Same for Imperial Sizing wax; 30+ yrs now, and never had a problem. And yes, I have (and do) used lanolin/alch as a sizing lube. In particular, on large batch case prep, run through a Dillon/Autodrive, set up for case processing. It works well, but leaves nasty shit everywhere that has to be cleaned up, and it sucks trying to get it into the case necks. There's no free lunch. Do what works for you.

Oh, and if you disagree with someone, be courteous about it. Otherwise, you just sound like a know-it-all asshat, that thinks the world revolves around what they know, ignoring what they don't know. And asshats tend to annoy me, which is never good for their longevity on this site.

Stand them up in a Tupperware container. Then it's easy to spray in the necks. I just lean my Tupperware against something at a 45 and start filling it like I would the hopper on my Giraud.

 

[JB.IC]

I wanted to comment on the behavior of sample ES at small sample sizes. It suffers the same consequence as sample SD. As can be seen below, sample ES can be underestimated much like sample SD when the sample size is small. Depending on the population SD, convergence onto the population value can be as small as 10 observations or as high as 30 observations. Since you do not know the population standard deviation, you have no idea how underestimated the statistic might be. Worse, the plots below show “on-average” results. No one is testing their rifle 500k times just to estimate a statistic. The minimums and maximums in the table illustrate how disperse any one test could be. As one would expect, more observations shrink the range between the minimum and maximum.

TLDR:
ES at small sample sizes are unreliable.