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

[David Christian]

I just wasted 30 minutes of my life trying to see if this thread was going anywhere…I will never get that time back.

 

[Beiruty]

I just wasted 30 minutes of my life trying to see if this thread was going anywhere…I will never get that time back.

Someone like Bryan Litz spend their life to be better at internal and external ballistics.
I recommend you buy his new book coming out in September

 

[Dave M.]

Dave,

I am an engineer, an experienced reloader, steel target shooter from 500 yards to 1270 yards, the longest at our club. I shot a couple of times at 2200 yards range.
My rifles could be anything from AR to 30" heavy barrel 300WM rifle.
My passion is to learn more and more about internal and external ballistics for small arms.

I do not compete for trophies.

You should definitely compete for trophies and see how your theory holds up long term against the others greats in the game.

 

[Dave M.]

Someone like Bryan Litz spend their life to be better at internal and external ballistics.
I recommend you buy his new book coming out in September

You realize there are dozens of shooters on this forum that likely know Bryan on a first name basis. Some true legends lurking on this forum, I’ve learned this first hand

 

[Beiruty]

You should definitely compete for trophies and see how your theory holds up long term against the others greats in the game.

I agree.

 

[johnfred1965]

You realize there are dozens of shooters on this forum that likely know Bryan on a first name basis. Some true legends lurking on this forum, I’ve learned this first hand

I hope that one horse's a$$ that has been posting on here is a legend. I'd hate to think I read all that BS from a regular shooter like me.

 

[Tarmacshooter]

I hope that one horse's a$$ that has been posting on here is a legend. I'd hate to think I read all that BS from a regular shooter like me.

Who is the horses ass?

 

[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