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OCW Guys… help me read these!

J

Jamesl0822

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Supporter
Minuteman
Feb 3, 2020
31
5
#1
6.5 cm
140 Berger VLD Target
All loaded at -.020 from Jam
42.1 - 43.9 grains of 6.5 StaBall

Help me choose the accuracy node by looking at these 100 yd groups.
4 shots each in a round robin fashion. 45 secs between shots, 2 mins between strings. No wind, maybe one bad trigger pull.

Thanks in advance
J
 

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#4
Warning - the results aren't perfect because the image of the target (and target itself) isn't perfectly flat (especially for 42.9 and 43.5), so the measurements are skewed.

Side note and question - is this 6.5cm or 6cm with the 109 Berger VLD? I'm only aware of a 6mm 109 LRHT. OCW isn't necessarily about finding the smallest group "node", it's more about finding a load range where the center of the group of impacts doesn't shift, even if the group sizes are larger.

OCW window would be 42.7 to 43.1 (discounted fliers), choose 42.9 and you'll have +/- 0.2gr allowable

Reason - center of the POI from POA range is 0.082 to 0.102 mil horizontal (0.02 mil difference), 0.047 to 0.012 mil vertical (0.035 mil difference). The differences in the center POI between the 3 charge weights is within most reticle subtension values (many are from 0.02 mil to 0.05 mil sizing).

If you have a center dot reticle subtension 0.03 to 0.05 mil of it's basically the difference between using the top portion of the dot to aim versus the bottom portion of the dot.

On either side of the window (42.5 or 43.3) you have a 0.048 to 0.071 mil center POI shift either vertical or horizontal (from one of the charge weight centers). A shift that is borderline or larger than many center reticle subtension.


1724537565856.png


1724550728564.png
 
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#6
Jamesl0822 said:
6.5 cm
109 Berger VLD Target
All loaded at -.020 from Jam
42.1 - 43.9 grains of 6.5 StaBall

Help me choose the accuracy node by looking at these 100 yd groups.
4 shots each in a round robin fashion. 45 secs between shots, 2 mins between strings. No wind, maybe one bad trigger pull.

Thanks in advance
J
Click to expand...
I'd choose 43.1 - 43.5 to retest to confirm that there's something good in there.
 
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#9
Evintos said:
Warning - the results aren't perfect because the image of the target (and target itself) isn't perfectly flat (especially for 42.9 and 43.5), so the measurements are skewed.

Side note and question - is this 6.5cm or 6cm with the 109 Berger VLD? I'm only aware of a 6mm 109 LRHT. OCW isn't necessarily about finding the smallest group "node", it's more about finding a load range where the center of the group of impacts doesn't shift, even if the group sizes are larger.

OCW window would be 42.7 to 43.1 (discounted fliers), choose 42.9 and you'll have +/- 0.2gr allowable

Reason - center of the POI from POA range is 0.082 to 0.102 mil horizontal (0.02 mil difference), 0.047 to 0.012 mil vertical (0.035 mil difference). The differences in the center POI between the 3 charge weights is within most reticle subtension values (many are from 0.02 mil to 0.05 mil sizing).

If you have a center dot reticle subtension 0.03 to 0.05 mil of it's basically the difference between using the top portion of the dot to aim versus the bottom portion of the dot.

On either side of the window (42.5 or 43.3) you have a 0.048 to 0.071 mil center POI shift either vertical or horizontal (from one of the charge weight centers). A shift that is borderline or larger than many center reticle subtension.


View attachment 8486960

View attachment 8487082
Click to expand...
 
#10
I totally mistyped 109gr… I’m also working on a load for my 6mm cm but it’s a lot easier to read.
The above test was with 6.5 140 gr VLD Target bergers… my apologies
 
#11
The only three charge weights in a row you have that don’t have a flyer are 42.3-42.7. I don’t think there’s enough information here to know anything, but if I had to go with something it would be with 42.5. 43.1 looks good by itself, but if you go one charge up or down shit gets weird. There’s no such thing as discounting flyers. The groups are what the groups are. Don’t waste too much time trying to find the perfect charge weight. Pick one and shoot it.
 
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#13
Evintos said:
Warning - the results aren't perfect because the image of the target (and target itself) isn't perfectly flat (especially for 42.9 and 43.5), so the measurements are skewed.

Side note and question - is this 6.5cm or 6cm with the 109 Berger VLD? I'm only aware of a 6mm 109 LRHT. OCW isn't necessarily about finding the smallest group "node", it's more about finding a load range where the center of the group of impacts doesn't shift, even if the group sizes are larger.

OCW window would be 42.7 to 43.1 (discounted fliers), choose 42.9 and you'll have +/- 0.2gr allowable

Reason - center of the POI from POA range is 0.082 to 0.102 mil horizontal (0.02 mil difference), 0.047 to 0.012 mil vertical (0.035 mil difference). The differences in the center POI between the 3 charge weights is within most reticle subtension values (many are from 0.02 mil to 0.05 mil sizing).

If you have a center dot reticle subtension 0.03 to 0.05 mil of it's basically the difference between using the top portion of the dot to aim versus the bottom portion of the dot.

On either side of the window (42.5 or 43.3) you have a 0.048 to 0.071 mil center POI shift either vertical or horizontal (from one of the charge weight centers). A shift that is borderline or larger than many center reticle subtension.


View attachment 8486960

View attachment 8487082
Click to expand...
I’m going to look closer at 42.5 - 43.3

Thanks for the ins
 
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#16
Jamesl0822 said:
6.5 cm
109 Berger VLD Target
All loaded at -.020 from Jam
42.1 - 43.9 grains of 6.5 StaBall

Help me choose the accuracy node by looking at these 100 yd groups.
4 shots each in a round robin fashion. 45 secs between shots, 2 mins between strings. No wind, maybe one bad trigger pull.

Thanks in advance
J
Click to expand...
 

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#20
Csafisher said:
It’s actually subject to quite a bit of error
Click to expand...
That's quite a bold statement and you may or may not be correct depending on a lot of factors. We can debate whether this method of reloading or any other method of reloading load development is "the best" or even works but in most cases if the end result is a load that works for the intended purpose then it probably works.

While the goal of load development is to find an accurate load that is also a high precision load, the way we ultimately determine what that load may be is by determining what loads don't work by a process of elimination and we want to get to that accurate load expending as little money, barrel life, components, etc as possible. In this case the OP gave some information on his load but not everything. He has a great bullet, but maybe not the best powder. We don't know what cases he used. He didn't give us any information on the rifle. It may be a custom rifle based on a BAT action or it may be a Thompson Center Compass. We don't know the shooters' ability. He could be a 1 MOA shooter or a .2 MOA shooter. Bottom line is I don't know what kind of dispersion to expect or what elements may be controlling.

Ultimately we are left looking at the target. In this thread they tend to reflect what most OCW targets tend to show. Statistically significant? Not even close. Subject to sampling errors? Yes. Shooter issues? Probably. In this case the 43.1 to 43.5 ranges shows a range of loads where the average point of impact for 12 shots seems to not move much implying the rifles was releasing the bullet on the same path since the expected velocity differences have almost no impact on the trajectory/drop at 100 yds (Most centerfire cartridges will move the point of impact about one caliber for a 100 fps change in velocity at 100 yds). Experience with OCW has shown that in most cases the loads that shoot well repeat about every 3% difference in charge weight and that scatter nodes occur when the difference is about 1.5% different than the OCW charge. Does this mean that the OCW is in that range? Anecdotally we can say this test does but to be sure we would need to retest in that range to see if it is repeatable. If it does then we have a load that is likely to be accurate and repeatable. Does it hold up at distance? Maybe. At distance we begin to see the effects of velocity variations. Usually an OCW load that fails at distance is due to velocity variations that probably are due to problems in the reloading process.

Is this load the best load? Who knows? The only way to determine that is to develop every possible combination of powders, bullets, cases and primers and shoot a statically significant number of each round and shoot them. Maybe in the end there may be clear winner or maybe not but we probably won't have any life left in the rifle so what is the point?
 
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#21
In a run of larger groups, you can accidently get a small group - but its neighbors call it out for what it is -- accident. On the other hand, a run of small groups is improbable and is - in my opinion - more likely to be telling you something.
 
#24
Csafisher said:
www.outdoorlife.com

Rifle Nodes: How You’ve Been Wasting Your Time and Money on Load Development

Everything you know about rifle nodes and load development might be wrong. Click here to see the results for yourself.
www.outdoorlife.com www.outdoorlife.com

Do nodes even exist??
Click to expand...
Yes, they do. It's a reference to the vibration of the barrel where the variance in barrel time releases the bullet from the muzzle where there's the least movement in that vibration. If this wasn't so, barrel tuners wouldn't work.

The big argument is really about just how hard or easy it might be to find just the right timing.
 
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#25
straightshooter1 said:
Yes, they do. It's a reference to the vibration of the barrel where the variance in barrel time releases the bullet from the muzzle where there's the least movement in that vibration. If this wasn't so, barrel tuners wouldn't work.

The big argument is really about just how hard or easy it might be to find just the right timing.
Click to expand...
Tuners don’t work. It’s been proven. Lol.
 
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#26
If OCW impact "nodes" don't work, you'd never be able to have a proper zero. If you're constantly re-zeroing your rifle because the center POI is shifting enough that you can dial the difference, maybe you should find a better load. 🤷‍♂️
 
#27
straightshooter1 said:
Yes, they do. It's a reference to the vibration of the barrel where the variance in barrel time releases the bullet from the muzzle where there's the least movement in that vibration. If this wasn't so, barrel tuners wouldn't work.

The big argument is really about just how hard or easy it might be to find just the right timing.
Click to expand...
I read this article with interest and on the surface the author seems to show that the OCW doesn't work. Unfortunately he doesn't show enough of his data to allow review of his effort. He also doesn't provide any real information on his reloading techniques.

One issue that clouds any test of this sort is the shooter. Especially any test that includes 30 shots. whether or not that is biasing the results we do not know.

In his final conclusions he evaluated mean radius as not changing significantly as his variable of interest to show that nodes don't exist after picking a charge based on consistency of point of impact. What he should have evaluated is the mean point of impact not mean radius. This is a flaw in his test analysis. Remember that OCW is not about group size (or mean radius) but about consistent point of impact being insensitive to charge weight.
 
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#28
On Friday, I shot a 5-shot group at 100. There were 4 in a little group - probably a 3, I didn't bother to measure it - with one shot (same elevation) that went left just out of the group. I know that some idiot wasn't paying attention when he shot that flyer. I know because that charge weight performed well three times in a row.

I had already picked the gun, barrel, powder, primer, bullet, and the seating depth. The barrel picked the bullet - it's a 1:9 30-cal so heavy bullets. I'm using Berger 230 hybrids. I chose the powder because I have some - H1000. Primer is 215M. Seating depth - fits my magazine.

How did I pick that group? I shot a 3-shots-per-charge ladder where the charge step was 0.3 grains. I looked at the ladder, found three smallish groups, more horizontal than vertical, that all printed in about the same place and picked the middle charge weight for more testing - the charge weights were 74.8, 75.1, and 75.4, I focused on 75.1. Then I loaded 3-rounds each with 74.8, 75.1, and 75.4 (that is, the same three charge weights that shot well before) and shot them. 75.1 still looked good. Then I loaded a several at 75.1 and shot that little group. Then I switched to 1,000, it shot well.

Whatever you do to come up with a charge weight to focus on, the magic - that is, the way you know it is good - is, it repeats. One demonstration is interesting. Two is nice but questionable. But if it shoots 3, 4, and 5 times - its a keeper. And if it stops shooting? Look some more.

I shoot ladders. I pick the best charge weight. I re-shoot that weight and the two either side of it, if try 2 fails that then the first try was an accident, keep looking. If it survives the initial ladder and the reshoot, then I re-shoot it and its neighbors again. It is survives try 3, its good. If it survived the original ladder and try 2 but fails try 3, I may run try 4 to see if it was me on an off day. If it doesn't repeat, then it isn't reliable and I go back to the original ladder and pick something else. That's me. You should do whatever you think is best.
 
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#31
Csafisher said:
Did you read the article? Or just dismiss it because of the magazine name?
Click to expand...
I have to question if you read the article. There are so many things wrong with this test and some of the author's conclusion.

For instance: "The theory of vibration nodes timed with bullet exit seems logical when an accomplished shooter and reloader is confidently lecturing you on the subject. But if this were true, your perfect node load would go out the window with any major change in temperature that altered your velocity. Ultimately, it just doesn’t hold up to large sample testing, not even a little bit."

This statement is bluntly in error. Vibration is a sinusoidal movement and the barrel is moving velocity is slower at the point of maximum travel and hence its position with time is changing less than when it is passing through is natural position at rest. Hence vibration theory would predict that there are points where the point of aim does not change as much with change in barrel time.

Another. "OCW Node: Based on accuracy, I pegged the OCW node at 22.3 grains because charge weights of 22.1, 22.3, and 22.5 grains had the closest consecutive mean points of impact (a .22-inch spread)"

His conclusion: "The lowest charge weight produced the tightest accuracy, and it slowly increased along with charge weight, with the book maximum producing the largest group size and mean radius."
and
Screenshot 2024-09-06 at 12.22.10 PM.png


Nowhere did he compare mean (average) point of impact to his original premise. He should have shot his 30 shots at 22.1, 22.3, and 22.5 gn. versus others. Also his point about group size increasing is based on the position of only 2 shots out of 30. Examining the mean radius the numbers do not appear to reflect a.change in precision (not accuracy) which is what he is trying to demonstrate.

He went to great trouble to calculate the mean radius for his data in test. However, not once did he bother to analyze whether or not the
mean radius differences were stistcically significant nor does he provide any data for his 30 shot mean point of impact.

I could go on but why bother!
 
#32
Doom said:
I have to question if you read the article. There are so many things wrong with this test and some of the author's conclusion.

For instance: "The theory of vibration nodes timed with bullet exit seems logical when an accomplished shooter and reloader is confidently lecturing you on the subject. But if this were true, your perfect node load would go out the window with any major change in temperature that altered your velocity. Ultimately, it just doesn’t hold up to large sample testing, not even a little bit."

This statement is bluntly in error. Vibration is a sinusoidal movement and the barrel is moving velocity is slower at the point of maximum travel and hence its position with time is changing less than when it is passing through is natural position at rest. Hence vibration theory would predict that there are points where the point of aim does not change as much with change in barrel time.

Another. "OCW Node: Based on accuracy, I pegged the OCW node at 22.3 grains because charge weights of 22.1, 22.3, and 22.5 grains had the closest consecutive mean points of impact (a .22-inch spread)"

His conclusion: "The lowest charge weight produced the tightest accuracy, and it slowly increased along with charge weight, with the book maximum producing the largest group size and mean radius."
andView attachment 8495827

Nowhere did he compare mean (average) point of impact to his original premise. He should have shot his 30 shots at 22.1, 22.3, and 22.5 gn. versus others. Also his point about group size increasing is based on the position of only 2 shots out of 30. Examining the mean radius the numbers do not appear to reflect a.change in precision (not accuracy) which is what he is trying to demonstrate.

He went to great trouble to calculate the mean radius for his data in test. However, not once did he bother to analyze whether or not the
mean radius differences were stistcically significant nor does he provide any data for his 30 shot mean point of impact.

I could go on but why bother!
Click to expand...
I agree there are issues. But even so I believe his conclusion is correct. There are other findings that show exactly the same - applied ballistics, hornady, RAD, etc. OCW is an old theory that everyone has accepted as fact so naturally people are biased and refuse to believe statistics and new evidence…..

Vibration theory is also a myth. This has been proven with numerous tuner tests and slo mo video. Even with pencil barrels.
 
#33
Csafisher said:
I agree there are issues. But even so I believe his conclusion is correct. There are other findings that show exactly the same - applied ballistics, hornady, RAD, etc. OCW is an old theory that everyone has accepted as fact so naturally people are biased and refuse to believe statistics and new evidence…..

Vibration theory is also a myth. This has been proven with numerous tuner tests and slo mo video. Even with pencil barrels.
Click to expand...
I must have missed those test. Can you reference them?
 
#36
Doom said:
Can you point me to one article/video where this was done?
Click to expand...
You’ll have to check out the RAD page or the AB book for those references.

Here is one website you can browse. He talks about the saterlee method specifically I believe. He also has a book called ammunition demystified. https://bulletology.com/

Here is a hornady podcast in which it’s mentioned. I believe they talk about in several other previous episodes. Maybe ep 50 idk.
 
#37
You made the claim. Copy and paste it from the website or quote the book.

If I had a nickle for everytime those hornady videos were used to support something they didn't say. 🤑🤣🤣

Nobody is talking satrlee method here. OCW and "satrlee method" are not remotely related.
 
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#38
supercorndogs said:
You made the claim. Copy and paste it from the website or quote the book.

If I had a nickle for everytime those hornady videos were used to support something they didn't say. 🤑🤣🤣

Nobody is talking satrlee method here. OCW and "satrlee method" are not remotely related.
Click to expand...
lol dude I don’t care. If you’re interested I pointed you in the right direction. You’re obviously not the type who would objectively look at information like that anyway.

Saterlee is not all that different from OCW when you look at large samples.

The hornady podcast I linked specifically mentions OCW so I’m not sure what you’re talking about….

😆😁😂 go read a statistics book…..
 
#39
Claiming the two are not all that diffrent just further proves you have no idea what you are talking about.

You didn't point anyone in the right direction. You hopped in a thread to answer a question you don't know the answer to, that nobody asked. Then sighted some information that doesn't support your supposition and refused to reference the other stuff you claim does.
 
#40
supercorndogs said:
Claiming the two are not all that diffrent just further proves you have no idea what you are talking about.

You didn't point anyone in the right direction. You hopped in a thread to answer a question you don't know the answer to, that nobody asked. Then sighted some information that doesn't support your supposition and refused to reference the other stuff you claim does.
Click to expand...
You’ve missed the point…. Continue reading your tea leaves lol.
 
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#41
Csafisher said:
You’ll have to check out the RAD page or the AB book for those references.

Here is one website you can browse. He talks about the saterlee method specifically I believe. He also has a book called ammunition demystified. https://bulletology.com/

Here is a hornady podcast in which it’s mentioned. I believe they talk about in several other previous episodes. Maybe ep 50 idk.
Click to expand...

I reviewed #50, #54, # 121, and nowhere is it mentioned that OCW or the Audette ladder do not work as intended. They do say that they don't change group size or mean radius (they can't keep their terminology straight). The Audette ladder doesn't involve group size at all and OCW as designed specifically warns against evaluating group size and being tricked by small groups. OCW basically is the equivilent of running 3 Audette ladders and run at 100yds to minimize the effects of any velocity variations showing up in the groups. The changes in the POI are due to the barrel pointing.

Csafisher said:
Vibration theory is also a myth. This has been proven with numerous tuner tests and slo mo video. Even with pencil barrels.
Click to expand...
Unfortunately you are wrong. Barrels do vibrate and tuners may work depending on your exceptions. If the exception is that the tuner will decrease group size then you will probably be disappointed. What does appear to happen is that the tuner can affect the point of impact. This allows the tuner to be used to correct for point of impact changes due to velocity/barrel time variations, typically due to ambient temperature. You might want to watch #110.

As for Jeff Siewert, I have read his book and conversed with him several times. Since you brought up Ammunition Demystified you might want to read the section on "Gun Dynamics".
 
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#42
I’m aware of what OCW is…. OCW is mentioned briefly in 121. And yes they keep the terminology straight. The point of all of this is small sample sizes. The OP and you can’t conclude which charge is best based on the data….

Barrels vibrate but not enough to make a difference and see it with OCW. The changes in POI is due to natural dispersion…. Not barrel pointing.

I’ve watched 110 and they didn’t conclude a weight or tuners work. Or at least not decisively.

Trying to pick a charge/barrel time with 3-5 shot groups and analyzing POI is a complete waste of time.
 
#45
You once again made the claim. You said barrels don't vibrate enough to cause POI shifts seen in OCW tests. Back it up or don't.... again.....

While we are at it, how big are the POI shifts seen in an OCW test? Inquiring minds want to know.


You understand saying POI shift in OCW is due to natural dispersion is the same as saying all powder charges shoot to the same POI. Which is false. Like common knowledge false.
 
#47
Csafisher said:
No it’s not….
Click to expand...
Explain how.....

Here is what we have from you so far.

PoI shifts in ocw aren't big enough to be explained by barrel vibration.

Poi shifts in ocw are due to natural dispersion.

A claim that isn't the same as saying all charges shoot the same poi. Feel free to explain your statements or answer the questions.....
 
Last edited:
#48
supercorndogs said:
Explain how.....

Here is what we have from you so far.

PoI shifts in ocw aren't big enough to be explained by barrel vibration.

Poi shifts in ocw are due to natural dispersion.

A claim that isn't the same as saying all charges shoot the same poi. Feel free to explain your statements or answer the questions.....
Click to expand...
The POI shifts yall are looking at in the small increments (+\- .2 or .3gr) is due to natural dispersion. Even if OCW actually worked, 5 shot groups isn’t anywhere close to enough data to think otherwise.

I did not say all charges shoot the same POI.
 
#49
You didn't. Your hypotheis requires it though.

(Below)So is there no poi shift here or is it natural dispersion making it look like there is one?
20240518_074044.jpg

(Below)Three more groups after rezero. I was shooting 28.5. So I had to move my zero down. I shot 100 or so rounds of 28.5 and 100 or so of the new one 30.5.
20240522_143159.jpg


20240527_073910.jpg


(Above)Shot two more groups after bedding the barrel and final tuneing and assembly. It's easily shot better than the dispersion in the ocw target.
20240614_080232.jpg

(Above)Here are a couple groups at 28.5. Looks like I was splitting time chronoing some 20 practical this day. This would have been inside the first 100 rounds down this barrel. Between 45 and 90. And earlier than the ocw and previous groups.
 
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