Single digit E.S. dont mean squat.

[Ninering62]

I have a load for my custom 25-06 that shoots 10 rounds all touching at 100 metres, but has an ES of over 100fps…the target tells the story!

Cheers.

only 100m.... take that out to 300m & 500m & watch it open up, then try that at 1000m & see what you have. Then you'll see why the guys are chuckling. I learned this exact same thing myself thinking that since I got nice tight cloverleafs or one ragged hole groups at 100yds with an ES like that T thought I was " good to go ".... until I went to 300 & 400yds which is the max I have at my home range. Bot was I wrong & did I get an eye-opening education.

 

[Ninering62]

Not many guys are truly honest about their ES anyway. Just like groups, a large sample size will probably tell a different story. I'm happy with a ES of 21 with a 50 shot sample.

I'm sure there are plenty of guys that will " stretch the truth " a lil bit about that, just like the guys that embellish how big their fish was & how much their deer weighed & scored. Me personally, I've never been one of those guys. The one good thing about being honest & just tellin the truth is ya never have to worry about exactly what you said or remembering what you said.

 

[epoletna]

I'm sure there are plenty of guys that will " stretch the truth " a lil bit about that, just like the guys that embellish how big their fish was & how much their deer weighed & scored. Me personally, I've never been one of those guys. The one good thing about being honest & just tellin the truth is ya never have to worry about exactly what you said or remembering what you said.

I'm surprised you'd say that. Long Range shooters wouldn't dare stretch the truth!

 

[QuietTexan]

Not many guys are truly honest about their ES anyway. Just like groups, a large sample size will probably tell a different story. I'm happy with a ES of 21 with a 50 shot sample.

Yup. If ES isn't ~5x of SD all it means is that there aren't enough samples in the population. Anyone can post up a 3-shot 0SD, 1ES is they shoot enough 3-shot groups. But when you add them all together ES will approach 5x SD, it's a mathematical certainty.

 

[vavaroutsos]

Yup. If ES isn't ~5x of SD all it means is that there aren't enough samples in the population. Anyone can post up a 3-shot 0SD, 1ES is they shoot enough 3-shot groups. But when you add them all together ES will approach 5x SD, it's a mathematical certainty.

While I generally agree with this, I wouldn't go so far as to say it's a mathematical certainty. That would require that the distribution is normal, which is probably correct most of the time. However, I have seen cases where the distribution is bi-modal (or something else).

 

[QuietTexan]

However, I have seen cases where the distribution is bi-modal (or something else).

Yes, I am making a base assumption that all the overlapping variables result in a normal distribution. I load on one press, with one powder measure, with matched cases, generally sort bullets, etc, so there shouldn't ever be two variables making a large enough impact to skew the distribution.

If someone was running something like two Matchmasters/powder drops side by side then there could very well show a bi-modal distribution of velocities. That's part of the reason I've never run two drops, and load complete batches at once. Something fun to consider intellectually, and shows why it's important to plot data.

 

[Culpeper]

Not sure if this has been mentioned, but ES is what happened in the past; whereas, SD is a predictor or model of what is likely to occur.

Yes, in a way for our purposes, but most people do it all wrong and we get into these lengthy old and tired arguments not to mention low confidence that lead to misleading results.

Okay, ES, AVG, and SD are statistic variables. The boundary is ES. As for SD, low standard deviation means data are clustered around the AVG, and high standard deviation indicates data are more spread out. All three variables work together. You can't have one without the others. It's in the formulas.

The data set is within the ES, which is our sample of an unknown population, which we want to predict. This is the only thing we think will likely occur for our purposes. With only one data set of 10 shots our the likelihood is low. Statistically, we need at least three 10 shot strings to get into likely. In statistics this is called Confidence.

The AVG is the mean of the data set
to calculate SD. And SD may sound like nothing more than the variance around the AVG but that too is incorrect. SD is the square root of the variance so that we can measure with the same units at hand.

For our purposes the SD is only useful if we have more than one data set. We can have two data sets with the same AVG but one with a high SD and the other with a low SD. If each data set was a string of 10 shots of the same load workup what does that tell you? Not much yet.

Chronograph are great but we still need to do the work. An old timer methodically shoots six 5 shots groups that average to .3 moa can say with 90% confidence that he has a 1/3 moa rifle and load. This can be done without a chronograph and no knowledge of elementary statistics and all the misinformation going around about how to use them. It would save a lot of people time and money.

 

[Culpeper]

Wow, what an interesting read. Where the heck did the "class" go on LRH? The inability to debate disagreement with class and dignity is such an indictment to what our society has become. "Karen" is alive and well here.

So for another 10 pages, EXTREMELY low ES FOR HUNTING to a distance where the bullet is rated for its OWN minimal performance velocity on game that you are are using, may not be such a big deal.

BTW in case anyone is interested, the Labradar per cent ERROR is +- 0.1% or +-0.1 m/s@1,000 m/s. So 6.56fps total potential swing shot to shot. So chronograph velocity numbers are not true as some think.


View attachment 484506

Do you know how to verify a Chrono advertised accuracy using weighted average? I don't want people getting the idea that their inexpensive Prochrono is a junk at 1%. I got it below 1% just using the hack of clear packing tape over the sensors.

 

[Mike Matteson]

Those days are long gone, it's sad

Get your heart off your sleeve. There are different ideas out there and what people think.
Don't take it to heart.
Never know when you might learn something.

 

[ButterBean]

Get your heart off your sleeve. There are different ideas out there and what people think.
Don't take it to heart.
Never know when you might learn something.

I strive to learn something new everyday

 

[DNADave]

I've had too much going on at work to really contribute here much lately, but this seems a topic where I can without too much brainpower expended.

@QuietTexan is right about sample size and I can see where @Culpeper was going, but I don't think the details are quite right.

If we assume that bullet speed per a fixed charge is normally distributed (and I have no idea whether it is or not), then the relationship between extreme spread (which is called the range in statistics), standard deviation, and the mean is as follows. The mean is a measure of central tendency: the value around which the data (our bullet speed) is centered. The range (or ES) is the set of values that define the lower and upper bounds of possible value for bullet speed (0 and infinity, we'll get to why later), and the standard deviation tells us how the data are distributed around our measure of central tendency.

Let's talk about standard deviation. A small SD indicates most values are close to the mean and a larger one means they become more disperse around the mean. If we assume a normal distribution, roughly 68% of the data will be within +/- 1 SD of the mean, 95% 2SD, and 99% 3SD. Once we get to around 5 SD we have pretty much captured all of the possible values with high certainty (but still not the range).

In statistics there are two versions of most summary statistics (mean, SD, range, median, etc.): the population version and the sample version. The population version is the universe of all data for that measurement. If you could record all bullet speeds for that charge then you would know the population. The sample is what you actually observe. If you are doing three shots and then calculating your statistics, then your sample is of size three. As you can imagine, if your sample size increases, your certainty of the veracity of the statistics increases and eventually becomes indistinguishable from the population versions. Think of creating a histogram (a bar chart with the y axis being the number of times a value is observed and the x axis being the values in increasing order from left to right). If you only take three measurements, then that histogram is not likely to be very accurate. In the same vein, taking 1000 measurements is likely more than you need to characterize the shape of the histogram. What is the right number depends on the range and the standard deviation (which we do not know ahead of time, unfortunately). So taking a reasonable guess for the sample size seems like an appropriate course of action.

Let's say we shoot 30 rounds and measure the speed of each one. We could create a histogram and inspect its shape. Assuming speed is normally distributed, does your histogram look like that normal bell shape curve? If not, maybe shoot 20-30 more times and then check. I would guess that you would need 50-100 rounds to really capture something that looks like a bell shaped curve. Take your mean and standard deviation of those 50-100 rounds and I think you could be confident of the performance of that particular recipe. 3x the SD will tell you what speeds you should expect 99% of the time (actually 99.7% of the time). I would not worry about range (or ES as it's know here) as long as 3x the SD gives you upper and lower bound numbers you can live with.

The important thing is that we have an appropriate sample size to have values we can trust. I would not trust a SD calculated from 3 values. Who knows what adding a fourth would do to the calculated SD. As you get into larger numbers, that adding a new number matters less and less. Hence trusting values from larger sample sizes more.

I don't know if this helps anyone or not, but I feel better now.

 

[Beluebow]

Delete.

 

[heat_and_fam]

Took my 6.5x300wsm out this morning wanted to shot 3 rounds through it just to verify since I'm taking it to Wyoming in Sept.
Here's a prime example of a load going off of single digit E.S doesn't mean anything, believe the target! E.S. WAS 21 FPS
One on the left was cold bore but could have been me to i shot this with my bi- pod I always do on my hunting rifles.

This is why the internet is stupid.

ES absolutely matters.
Barrel harmonics/accuracy node also absolutely matter.

If you want the most repeatable and accurate load, you need to find both… simultaneously and at the the same time.

 

[L.Sherm]

Did everbody forget what the original title was SINGLE digit E.S don't mean squat?
As usual thread gets off in the weeds just like most anymore, the point was I have read many times were reloeaders get obsessed with single digit E.S. and was just trying to prove a point that repeatedly and what the target says is the most important thing instead of what numbers say. Then we get to well it matters past 1,000 well that might be true but is it 1200, 1500, or 2000 only way you will know is TEST which I do alot!