Vertical Dispersion: Flat spots on the MV ladder test are meaningless

[CA_Shooter]

I go with at least 5-shots so the MV SD would be meaningful. Also, 5-shots groups would give an indication for about the dispersion of the bullets.

I'm not trying to throw gas on the flames here, but using a 5 shot sample size for FPS is very much meaningless when it comes to SD.

Especially considering, using a Magnetospeed for example, Magnetospeeds own website states they are between 99.5% and 99.9% accurate. That can be an ES of 14 for a bullet going 2800 FPS...just with the chronograph.

Conflate that with small differences in brass, bullets...and possibly other unseen things, and with 5 shots you can easily get meaningless SDs.

And it's important to point out your theory hinges on SD as something like 35% to 65% of your theory.

I think the reason many people gravitate to the theories that use FPS SDs to figure out what load to pick is that picking a load is hard and an abstract problem. And people like the idea of being able to have a chronograph concretely solve the puzzle for them is very enticing.

 

[Beiruty]

I'm not trying to throw gas on the flames here, but using a 5 shot sample size for FPS is very much meaningless when it comes to SD.

Especially considering, using a Magnetospeed for example, Magnetospeeds own website states they are between 99.5% and 99.9% accurate. That can be an ES of 14 for a bullet going 2800 FPS...just with the chronograph.

Conflate that with small differences in brass, bullets...and possibly other unseen things, and with 5 shots you can easily get meaningless SDs.

And it's important to point out your theory hinges on SD as something like 35% to 65% of your theory.

I think the reason many people gravitate to the theories that use FPS SDs to figure out what load to pick is that picking a load is hard and an abstract problem. And people like the idea of being able to have a chronograph concretely solve the puzzle for them is very enticing.

If you study
1) fluid dynamics,
2) Finite Element Analysis,
3) Internal, external ballistics
4) Harmonics in metals,
5) Waves, resonance theory and its applications,
6) First order and second order system modeling,
7) Static and dynamic effects in system modeling,
8) and finally statistics,

Then, one should know a word or two in the subject of internal ballistics modeling.

I guess more than 50% of those who read this thread, never read the OFPS theory paper I posted.

 

[CA_Shooter]

If you study
1) fluid dynamics,
2) Finite Element Analysis,
3) Internal, external ballistics
4) Harmonics in metals,
5) Waves, resonance theory and its applications,
6) First order and second order system modeling,
7) Static and dynamic effects in system modeling,
8) and finally statistics,

Then, one should know a word or two in the subject of internal ballistics modeling.

I guess more than 50% of those who read this thread, never read the OFPS theory paper I posted.

So.....

#1 through #5 are irrelevant when speaking about sample sizes.

I know #8, statistics. I've also run sample size shot theory by a buddy of mine that creates AI simulations. His graduate degree was also focusing on simulations.

Back when I first started loading my own rounds, I wanted decent enough sample sizes and so I used .2 grain increments and shot anywhere between 10 to 20 shots per load with a chrono. I figured I needed the practice anyhow. With the high sample size, the data was very erratic and didn't suggest anything very consistent

A 5 shot SD is NOT anything of consequence... Period

 

[Tarmacshooter]

If you study
1) fluid dynamics,
2) Finite Element Analysis,
3) Internal, external ballistics
4) Harmonics in metals,
5) Waves, resonance theory and its applications,
6) First order and second order system modeling,
7) Static and dynamic effects in system modeling,
8) and finally statistics,

Then, one should know a word or two in the subject of internal ballistics modeling.

I guess more than 50% of those who read this thread, never read the OFPS theory paper I posted.

I guess I’m still failing to see what your point, question or contention is.

 

[Dave M.]

I'm not trying to throw gas on the flames here, but using a 5 shot sample size for FPS is very much meaningless when it comes to SD.

Especially considering, using a Magnetospeed for example, Magnetospeeds own website states they are between 99.5% and 99.9% accurate. That can be an ES of 14 for a bullet going 2800 FPS...just with the chronograph.

Conflate that with small differences in brass, bullets...and possibly other unseen things, and with 5 shots you can easily get meaningless SDs.

And it's important to point out your theory hinges on SD as something like 35% to 65% of your theory.

I think the reason many people gravitate to the theories that use FPS SDs to figure out what load to pick is that picking a load is hard and an abstract problem. And people like the idea of being able to have a chronograph concretely solve the puzzle for them is very enticing.

I’ve always felt the same way about chrono data. People put WAYYYY too much stock in it. Chrono data should be used as an ancillary piece of data to make minor decisions between adjacent groups and/or nodes. I have always allowed the target to talk to me. People that make decisions on their load development based primarily on MV and ES/SD data are always chasing their tail when their rifle, with its incredibly low 10 shot SD of 3fps, won’t group on the target.
Dave.

 

[Alex Wheeler]

The issue with saying this way or that way is or is not valid is that different barrels tune up differently. Sometimes its in a spot that is stable with velocity some times its not. Sometimes the poi is stable some times its not. At the end of the day all that matters is that the group is small and repeats. How you get there is always going to be a debate. I personally do everything at 1k or 600 if its a light hunting rifle. Doesn't matter if its a magnum or br rifle. I find a ladder very useful for finding an area to start shooting 3 shot groups. Yes, I only shoot 3.

 

[Webster]

Load 10, 11 was selected as a candidate for best vertical dispersion
Load 17 was then selected as another candidate.

Load 17 won and was selected as the best load for this rifle/powder/bullet combo
View attachment 1364222

I plotted your data in Excel and asked it to calculate error bars. I assume each data point is 1 shot. Excel calculates you have an extreme spread of about 20 fps which your chart ignores.

 

[BartsBullets]

Let’s not get too carried away here. Blind squirrel finds a nut every now and then.

You’re a pretty badass Squirrel my friend!

 

[Webster]

If you study
1) fluid dynamics,
2) Finite Element Analysis,
3) Internal, external ballistics
4) Harmonics in metals,
5) Waves, resonance theory and its applications,
6) First order and second order system modeling,
7) Static and dynamic effects in system modeling,
8) and finally statistics,

Then, one should know a word or two in the subject of internal ballistics modeling.

I guess more than 50% of those who read this thread, never read the OFPS theory paper I posted.

Small groups are all that matters. Forget everything else. No human can pull all the above subjects together to make a small group.

 

[Alex Wheeler]

I’m brand new to the term as of Keith’s last video. All I know of PC is that Keith says no at long range, a top .22 guy said no, meaning short range, and some years back, Alex Wheeler and many said yes, it’s the way that groups are smaller than SD/ES suggest. I had searched a thread here.

And years later, after shooting and seeing a LOT more load development targets shot at 1k since then I still say YES!!!! Thats why 1"s at 1k happen imo. Since the lab radar came out I use a chrony often. I dont care what it says but I do look at it. I would say if I had to tune by chrony numbers only, Id want an es of 12.

 

[Beiruty]

First on the block with latest Bryan Litz Book Volume 3

 

[Beiruty]

 

[Beiruty]

Bryan Litz dedicated a full chapter, 6 for ladder testing for accuracy.
Under the fair use clause, here is a summary that supports the claim of this thread and supports the conclusion of the OFPS theory, seeking the lowest MV SD

 

[gunsandgunsmithing]

Bryan Litz dedicated a full chapter, 6 for ladder testing for accuracy.
Under the fair use clause, here is a summary that supports the claim of this thread and supports the conclusion of the OFPS theory, seeking the lowest MV SD

View attachment 1367979

1%, as in .3 increments? That should be enough to bring this thread to life. How much money has been spent on scales to weigh within .01 of a grain and how many are splittling kernels?

 

[Alex Wheeler]

.3% is about right for long range BR. Thats about one tenth of a grain in a 6bra. A lot of guys are going finer yet. 1% in LR BR is roughing in. I will go as course as .5% in the big magnums at LR. 1% is way too big at long range. If low es is your goal I wont argue because its not something I care about. Theres many different goals when it comes to tuning. Since we are talking ladders I will assume we are talking LR accuracy. That advice in your book is wrong. A pile of records support that statement. Now, in part I agree. Groups are better than ladders, but 1% is huge.
I dont like getting into these threads, but I also like to make sure people get good info. No matter what your needs are, find a successful person thats does it and ask them. If your into LR BR ask a winning LR BR shooter, if your into SR BR ask a winning SR BR shooter. If your into F-class ask a winning f-class shooter. If your into LR hunting ask a guy that is having success tuning his rifles. You want advice from those that are doing it and proving it.

 

[Bc'z]

I'll have to get a copy of that book for my targets to read.
Maybe afterwards my targets will have a better understanding of what they are supposed to look like.

 

[LVLAaron]

To be fair, the non-highlighted part of the book says it's unreliable... And why I run the same ladder several times (all details and graphs posted earlier in the thread) But, I'm just an F-Classer.

I will not argue or defend that my way is the right way, but it's gotten me pretty far, so I stick with it... and I think you'd be hard pressed to find an FTR guy who says the sweet spot for juggernauts isn't 2725-2750 in a 30 inch barrel.

If your into LR BR ask a winning LR BR shooter, if your into SR BR ask a winning SR BR shooter. If your into F-class ask a winning f-class shooter. If your into LR hunting ask a guy that is having success tuning his rifles. You want advice from those that are doing it and proving it.

/thread

 

[Dave Way]

I'll have to get a copy of that book for my targets to read.
Maybe afterwards my targets will have a better understanding of what they are supposed to look like.

When I started reading your post, I read the first part as “I’ll have to get a copy of that book for my target.” !

Sorry. Just where my brain went. Bottom line is information is just that, information. Some is good, some is bad and sometimes it is hard to distinguish the difference. With all the variables involved whatever you are told may not, and probably will not, apply in your particular situation with your particular rifle and cartridge. In the end the paper tells the story.

Dave.

 

[CharlieNC]

Bryan Litz dedicated a full chapter, 6 for ladder testing for accuracy.
Under the fair use clause, here is a summary that supports the claim of this thread and supports the conclusion of the OFPS theory, seeking the lowest MV SD

View attachment 1367979

I don't have the book, but this excerpt alone is not clear. It seems to infer a single shot ladder is not suitable using a Chrono, and that a number of shots are required for statistical significance; in my experience that would be 10. That's a lot to cover the fine increments. It also mentions charge ladder test on a target, but nothing more?

 

[Bc'z]

When I started reading your post, I read the first part as “I’ll have to get a copy of that book for my target.” !

Sorry. Just where my brain went. Bottom line is information is just that, information. Some is good, some is bad and sometimes it is hard to distinguish the difference. With all the variables involved whatever you are told may not, and probably will not, apply in your particular situation with your particular rifle and cartridge. In the end the paper tells the story.

Dave.

Yes sir, we can have in depth discussions, talk hypothetically, share information for discussion and analysis, but when it comes right down to it the only paper worth reading is the 1 we just poked holes in.
1 thing I've learned is all the different disciplines have a different methodology in which to achieve thier goal, and not all methods fit every discipline.
Finding tid bits of method to apply to ones practice/ development can be beneficial but is not the end all be all.