powder ladder??

[Link]

Stoldt this graph to ask Would you use 53.5 as a starter because if you go up or down you come close to the water line? How about the same with a seating depth?

 

[ELR LVR]

Caliber, Bullet used, etc?
What weight would theoretically be a max load?

 

[Link]

Caliber, Bullet used, etc?
What weight would theoretically be a max load?

I just picked that graph as a example for my question. I guess a question would be - is that a node.
ty Don

 

[ELR LVR]

I just picked that graph as a example for my question. I guess a question would be - is that a node.
ty Don

Good question
But I don't believe one can determine a "Node" simply by velocity leveling out
I have seen where a rifle shoots great but with Extreme spreads of 50 fps
And the rifle shoot not so great but with SD's in the single digits
------------------------------------------------------------------------
The only way I know to tell if you're in a Node is by coordinating the bullets exit timing with the muzzle
And by how it prints on target
And then by checking the consistency of how it prints on target on different days.
------------------------------------------------------------------------
What it does look like though, is a way to tell your powder charge is near optimum, not erratic etc.

Following though, since I do believe it's a good question others may have more info on.

 

[ShtrRdy]

There are not enough samples at each point to make a choice/decision.

 

[jelenko]

There are no velocity 'nodes'.
To find an accuracy node you look for group size vs incremental powder charges/seating depth.

 

[Clancy]

This isn’t really a ladder. This is just plotting the fact that if you add more powder you’ll get more velocity. You’ll see some flat spots, sure. May or may not see them in the same place next time. I do most definitely believe bullets have happy speeds (nodes) but this isn’t how I’d find them.

What really matters is overlapping impacts from different charge weights, and a target with bullet holes is the only way you’re going to see that. You’ll notice that (imaginary numbers) charges that yield speeds between 3200 and 3230 fps overlap. Shoot for 3215. No need for a chart.

 

[Straightshooter1]

I just picked that graph as a example for my question. I guess a question would be - is that a node.
ty Don

Answer: No!

You need to rely on your target results to identify a node.

If one shoots a series of the same charges for charting velocity from powder charges, a different looking graph appears for each of the series and if one is close to the same, that's more of a simple coincidence. The more of them you shoot and graph the more the line becomes a simple linear line all together.

Here's an example from Bryan Litz book where he tested this type of ladder testing:


Here's a couple others like that:

 

[ELR LVR]

Easiest way I know to identify a node, at least a good forgiving one
is mainly by seating depth
not by powder charge
Once I am good on seating depth I can vary my powder charge by full grains and it wont matter much as far as accuracy and precision goes.
Meaning I can adjust my velocity if my seating depth is good
------------------------------------------------
When my seating depth is in a good node, I am usually able to vary seating depth ....
....by as much as .005" in and .005" out and the groupings will pretty much stay the same (tight)
POI will stay the same
Thats a node
------------------------------------------------
This is a wildcat I am developing at the moment
The powder charges are a full 1.0 grain apart
I started at a 25.0 grns safe point and worked up 1.0 grn at a time
Bottom hole is 27.0 grns then I moved to a different POA and continued my ladder test
28.0, 29.0, 30.0
at 30.0 it gave stiff bolt lift
I arbitrarily chose a seat depth at .010" off the lands as a starting point
since this is a common starting point barrels seem to like but is not a hard fast rule
You can tell just by all POI's being pretty much the same across the board that I am close to a node
REGARDLESS of powder charge
--------------------------------------------------
So as everyone is saying here,
How your bullet prints on target is the best way to find a node
Varying powder charge/primer is how you hone your SD's down
If you cannot hone your SD's down at 15fps or less, then change powder
Usually best SD's are found when close to max charge, but not AT max charge

 

[JEFFPPC]

Easiest way I know to identify a node, at least a good forgiving one
is mainly by seating depth
not by powder charge
Once I am good on seating depth I can vary my powder charge by full grains and it wont matter much as far as accuracy and precision goes.
Meaning I can adjust my velocity if my seating depth is good
------------------------------------------------
When my seating depth is in a good node, I am usually able to vary seating depth ....
....by as much as .005" in and .005" out and the groupings will pretty much stay the same (tight)
POI will stay the same
Thats a node
------------------------------------------------
This is a wildcat I am developing at the moment
The powder charges are a full 1.0 grain apart
I started at a 25.0 grns safe point and worked up 1.0 grn at a time
Bottom hole is 27.0 grns then I moved to a different POA and continued my ladder test
28.0, 29.0, 30.0
at 30.0 it gave stiff bolt lift
I arbitrarily chose a seat depth at .010" off the lands as a starting point
since this is a common starting point barrels seem to like but is not a hard fast rule
You can tell just by all POI's being pretty much the same across the board that I am close to a node
REGARDLESS of powder charge
--------------------------------------------------
So as everyone is saying here,
How your bullet prints on target is the best way to find a node
Varying powder charge/primer is how you hone your SD's down
If you cannot hone your SD's down at 15fps or less, then change powder
Usually best SD's are found when close to max charge, but not AT max charge

In the br game you are in a spot lower than last after all that. What are you doing?

 

[ELR LVR]

In the br game you are in a spot lower than last after all that. What are you doing?

IE:
I find seating depth first
then adjust charge weight second
Thats how I get loads that do this
In just about
EVERY
CALIBER
I
OWN and BUILD
And when I state "In a good Node" that is to mean a forgiving one as opposed to a tight finicky one
There is more than one Node in case you weren't aware
A Node where if you are out .003" in seating depth is NOT a forgiving node. If I can vary .005" in or out and not much changes then I know I am in the center of my node (Exit Timing) with respect to seating depth
---------------------------------------------
Maybe we need to post a thread or get with the forum boss to finalize what this website is actually called because most 90% of every member here seems to confuse this place with Benchrest . com
let me you ask you
Is this forum called
ACCURATE SHOOTER
or
Competition only shooter?
----------------------------------------------
But go ahead and fill me in on what I'm doing wrong
I'm taking notes

 

[ELR LVR]

While I'm taking notes:
Perhaps you'd like to give me a few pointers on how to shoot a pistol?
cuz this is about as good as I can do off hand with a 1911 at 33 yds

 

[Gil P.]

Good question
But I don't believe one can determine a "Node" simply by velocity leveling out
I have seen where a rifle shoots great but with Extreme sporeads of 50 fps
And the rifle shoot not so great but with SD's in the single digits
------------------------------------------------------------------------
The only way I know to tell if you're in a Node is by coordinating the bullets exit timing with the muzzle
And by how it prints on target
And then by checking the consistency of how it prints on target on different days.
------------------------------------------------------------------------
What it does look like though, is a way to tell your powder charge is near optimum, not erratic etc.

Following though, since I do believe it's a good question others may have more info on.

This is one of the best and most concise explanations of the OPs question I've yet seen.

ELR LVR has a good brain.

 

[bobinpa]

I don't understand.... In order to adjust seating depth, don't you have to have a "pretty close" charge weight? How do you determine what charge to start with before you start with seating depth? I feel like a dog chasing my tail sometimes...

 

[ELR LVR]

.......How do you determine what charge to start with before you start with seating depth? I feel like a dog chasing my tail sometimes...

Loading manual is a good place to start
Compare cartridge size to another of similar size then, use a load known for your known cartridge
One example would be going from a 243 to a 243 AI
You can use a known safe load for 243 when developing a starting load for the 243 AI
-------------
IE: the wildcat I am working on I found the Grains capacity of the case to be 30 grns
I know the case is larger than a 223 but slightly smaller than a 22BR
...............If I dont have a manual to reference from. I can START with a known safe load for the slightly smaller case being a .223 then work up.
Which is 25.0 grns of W-748

So I started with 25.0 and worked up until I experienced pressure signs
.....so as to also find the max load
to stay away from it.
So when starting at 25.0 grns It shot well but felt pretty mild which it should have because that is
the (Smaller cased .223 load) and knew it would actually call for more powder being a slightly bigger case than the 223.
Once I got to 27.0 grns it felt right and shot well
and as I approached 30.0 grns the sound started to become different, more sharp and recoil was slightly more noticeable etc and I knew I would be experiencing max soon
sure enough at 30.0 grns that was max
So the optimum load being at 27.0 grns is about right being 3 grains under max
Now of course I have to finer tune that by then working in 1/10ths of a grain up from there to perhaps 28.0 grns (Still staying safely away from pressure signs.)
---------------------
Very often you will read or hear guys say
"I started getting pressure signs so I just backed it off a grain"
This is often all that's required to be safely under max and is also often the optimum charge,
or darn near close to it.
In this case me being 3 grains under is def safe with respect to the size of the case capacity and the percentage difference of charge weight from 30.0 to 27.0.
----------------------
You need to be able to read ALL, the pressure signs not just one
Head expansion, Reading the primer etc.
A primer can start to flatten and that's alright
As long as the head is not expanding, (read the head in 1/10ths with a mic and compare to a sized case)
You do not want the head to be expanding at all
If you are within safe charge limits the head /web area should stay the same dia. as when it is F.L. sized
----------------------
While doing this you want to read your velocity
if you are 100 fps slower than where you should be but get pressure signs
you need to go to a little bit slower powder and start over again with this
If your velocity is where it should be and SD numbers are where you want it to be.......
.......Now you go back to adjusting and finalizing your seating depth since your charge weight is targeted.
-----------------------
In my 22 BR's I can be anywhere from 3550 to 3800 fps with bullets anywhere from 50 grns to 60 grns
But still shoot good because the seating depth is correct
-----------------------
In the 22 BR's I have developed Loads using 3 or more different powders,
W-748, SRB-118, AA2520 to name a few
that all shoot in the .2's or better, Because I keep the same seating depth once I've found it.
This makes it nice because you kind of want options with powders when sometimes the market is sold out on your go to favorite powder,

 

[RegionRat]

I guess a question would be - is that a node.

No, it is certainly not a "node". A velocity plot is never used to establish a "node".

ETA: I was warned to be even more clear... a single shot ladder velocity plot is never used to establish a "node". The word "node" can cause confusion. It was borrowed from structural dynamics where it does have a meaning, but in this context the performance observation would be better described as a "tuned load". And "tuned load" assumes that you can also show the out of tune load exists.

Now, say if that plot was the "vertical impact" from a common aimpoint at some distance way out on the trajectory and the lower axis was the powder step. If every step on the left axis was say 1 inch of vertical at 800 to 1000 yards, then we would go back and test 53.75 against 55.25 and see which one is better (more forgiving) in reality. In reality, the group size and POI (point of impact) stability is the goal.

Before you hung your hat on it, you would "ladder" a sweep of seating depth using the 53.75 charge just to see if using a different seating depth was a better starting point.

Sometimes but not always, there is no correlation to the velocity stats, but lets face it, when the target looks good at distance, and more than one distance, then the velocity stats are "good enough" be by definition.

Regardless, when we say velocity stats the implication is that you have a valid statistic for a given recipe. That doesn't come from a single shot, or five shots. It generally takes 30 or more test shots to have any clue what the recipe will really do, and best if those tests are from multiple days. The assumption here is different than BR shooting or when you can adjust the load to the daily conditions. The assumption is to pre-load the ammo.

As in the post by Straightshooter1, the Audette Ladder Test is very different than the Satterlee 10-shot.
The Audette uses the shot-fall on the target, not the chronograph.

By the way, the vertical ladder test existed long before it was named The Audette Method. In university level libraries with good collections, you can find papers going back to the late 1800's where harmonics and compensation were being investigated and they used "ladder" tests with vertical shot-fall plots.

The same method is used on heavy weapons tests to this day.

In order to adjust seating depth, don't you have to have a "pretty close" charge weight? How do you determine what charge to start with before you start with seating depth?

You can select which order to investigate first, depth or charge.
Let's assume you know a safe charge weight range. You can then do a depth sweep by picking a middle of the road charge to start.

Then you would follow up with charge ladder and verification testing.

If the waters are not well charted and there is danger, you start with pressure (charge) and then depth, followed with verification testing.

 

[Webster]

Stoldt this graph to ask Would you use 53.5 as a starter because if you go up or down you come close to the water line? How about the same with a seating depth?
View attachment 1663216

There is no water line or flat spot. It's an inaccurate graph because there is not enough shots at each powder charge. If you plotted 25 shots at each powder charge you would have an almost straight line thru the average for each group. Even if you had a straight line plot the data won't tell you what the group size would be with each charge. Small groups are shot with a big ES at 100-200 yards. Small and round is all that matters.

 

[ELR LVR]

No, it is certainly not a "node". A velocity plot is never used to establish a "node".

Now, say if that plot was the "vertical impact" from a common aimpoint at some distance way out on the trajectory and the lower axis was the powder step. If every step on the left axis was say 1 inch of vertical at 800 to 1000 yards, then we would go back and test 53.75 against 55.25 and see which one is better (more forgiving) in reality. In reality, the group size and POI (point of impact) stability is the goal.

Before you hung your hat on it, you would "ladder" a sweep of seating depth using the 53.75 charge just to see if using a different seating depth was a better starting point.

Sometimes but not always, there is no correlation to the velocity stats, but lets face it, when the target looks good at distance, and more than one distance, then the velocity stats are "good enough" be definition.

Regardless, when we say velocity stats the implication is that you have a valid statistic for a given recipe. That doesn't come from a single shot, or five shots. It generally takes 30 or more test shots to have any clue what the recipe will really do, and best if those tests are from multiple days. The assumption here is different than BR shooting or when you can adjust the load to the daily conditions. The assumption is to pre-load the ammo.

As in the post by Straightshooter1, the Audette Ladder Test is very different than the Satterlee 10-shot.
The Audette uses the shot-fall on the target, not the chronograph.

By the way, the vertical ladder test existed long before it was named The Audette Method. In university level libraries with good collections, you can find papers going back to the late 1800's where harmonics and compensation were being investigated and they used "ladder" tests with vertical shot-fall plots.

The same method is used on heavy weapons tests to this day.

You can select which order to investigate first, depth or charge.
Let's assume you know a safe charge weight range. You can then do a depth sweep by picking a middle of the road charge to start.

Then you would follow up with charge ladder and verification testing.

If the waters are not well charted and there is danger, you start with pressure (charge) and then depth, followed with verification testing.

Everything said here
"It generally takes 30 or more test shots to have any clue what the recipe will really do, and best if those tests are from multiple days."
With heavy emphasis on his mention of where he said to test on multiple different days.
Also very much agree with this....
You can select which order to investigate first, depth or charge.
Let's assume you know a safe charge weight range. You can then do a depth sweep by picking a middle of the road charge to start.

There's no Law in the Penal Code that states one must start with Seating Depth first,
That's just my personal choice because I find my load faster that way using less components
A person can tune their charge weight first if they want then go to seating depth.
I can pretty much find a good load within 20 rounds now.
When it used to take me maybe 100 rnds.
----------------------------------------------------------------------------------------------
When I "THINK" I've found a good load, I continue to shoot and test that one load.
It does not mean....
.............That I cannot shoot or test other different loads or even different seating depths ALSO
but it does mean to keep testing and gauging your "Magic Load"
repeatedly on different days (Meaning every time I go out which will be different ambient conditions
.... to test and gauge that loads consistency
----------------------------------------------------------------------------------------------
since if it only shot good the first time out, it could lead a guy to think he found the load
but that cannot be finalized unless it repeats itself from day to day.
A lot of our practicing on target is not just practice but keep testing to ensure that certain ONE load repeats itself on target.
When testing Long Range Loads,
I will repeatedly test at 600, 1000, 1200, then go back again to 600
if it repeats through the gammut, I call it good.
My go to load has stayed the same for hundreds of rnds, keeping the same seating depth and performs the same as 5 yrs ago when I developed it
--------------------------------------------------
Pic 1 was my son shooting this rifle at 580 yds for his first time at long range back in 2020
I like taking someone who does not or has never shot 600 yds and let them shoot my rifle
because when someone that does not shoot 600 prints about a 3inch group, thats a good load.
2nd pic is then me shooting the rifle at 580 yds in 2020 to show him how to tighten it up a bit
I tested it again recently and it shot the same at 580 yds last week.
--------------------------------------------------
So it is a very good indicator to Repeatedly test your newfound best load, to make sure on any given day any given year it will basically perform the same from Winter at Christmas to Spring in May.
Waterline being the same, group size being the same

 

[Doom]

Stoldt this graph to ask Would you use 53.5 as a starter because if you go up or down you come close to the water line? How about the same with a seating depth?
View attachment 1663216

I stared this yesterday morning but didn't finish. Both @RegionRat and @Straightshooter1 have hit this issue well. I am going to kinda dump on you but please don't take this personally. It it based on frustration with this whole concept of velocity flat spots and if they exist and why or why not. Hopefully my comments will give you a little more perspective on why flat spots show up in data and why basing any decision on them is in error. And yes it does have to do with the amount of data but also the fallacies in the design of the 'test".

First of all, the whole premise of adding energy and that energy not ending up in velocity is a violation of the first law of thermodynamics. Unless the energy goes to heat loss, unburnt powder, or energy in the gasses it is going to show up in the velocity. The physics associated with losses and combustion that would cause a sudden change in those losses (proportional to load) does not cause this to happen.

For this flat spot to occur in reality would most likely occur in the case where the powder does not combust (actually Deflagrate) uniformly. This can occur when the case fill is not high enough and the powder differs in orientation from shot to shot. This is why it is desirable to have a fill greater than 90%.

In the case you posted, I am guessing based on the scatter for a 0.5 gn variation in charge you are showing a singe shot for each load. Based on your data a half grain of powder will produce about 22-23 fps variation in velocity. This is typical of most powders used in larger cartridges like the 308 and larger, with a range of about 60 per grain for the 308 down to 45 per grain or so for the larger magnums. If you were to shoot multiple rounds of a given charge AND you can load Standard deviation of 8 fps, then 95% of you single shot velocities would fall within approximately +/- 16 fps of an average. Any one shot has a 50% chance of being above (or below) the average. Additionally your increment is only expected to produce +/- 11 fps. With a single or even 3 shots there is no way to know where within that range you are.

I hope this helps.

 

[JFrank]

A guy would need to compare the target to the graph to determine if this similar velocity area is a pause in vertical displacement.

The target is king.