Load Development Confirmation

[Sixgun]

This pic...top row only..was the the best ES and SD numbers of the first set which was 39g and 40.5.
From 39g..groups 1, 2 and 3 are 38.8, 39 and 39.2. Groups 4-7 are 40, 40.2, 40.4, and 40.6g.
The 2 dots in the middle are sighters the bottom row I was testing an EC tuner brake with 140 Berger hybrids over 37.7g Varget with BR4 primers. All the other groups are 144 Berger hybrids with H4350 and cci 450 primers...these are what I'm really testing.

 

[big5ifty]

The first string I was doing an OCW test.. ..but I think the ES and SD numbers are more important than group size.

For an OCW test, you can ignore ES and SD.

Look for overlapping group centers with 3 incremental powder charges each roughly 1%. The middle one of the 3 is either where it's at or close to, and you can verify that by shooting it again with two groups 0.5% either side of it.

Looks to me 39g of H4350 with 144 Bergers is the one to have. What do you guys think?

I think 40.2 . The three group centers 39.9 to 40.5 seem centered a smidge to the right of the 1 o'clock line and have what appears to be the same elevation.

It's a quick, easy and reliable verification test to reshoot 40.1, 40.2 and 40.3 and confirm you have overlapping group centers.

If you feel that 39 is the one, reshoot it next to 39.1 and 38.9, but 39.6 looks to me like or close to the scatter node, so the OCW node is either around 40.2 or 39.0 .

All you want to see is overlapping group centers. It's very easy to get emotionally attached to group sizes in an OCW test, but put your feelings aside and look purely for overlapping group centers.

The group size can be tweaked later with seating depth changes.

 

[Sixgun]

This one I was doing a standard ladder test with the respective charge weights of the second test 38.2, 39, 39.2 40, 40.2, 40.4 and 40.6.

On the second grouping test i marked the shots in each group 1, 2, 3, 5. These are the forth rounds of each charge weight. I had to do it this way because a couple of yahoos showed up at the range shooting AR's with varmit scopes and spotting scopes shooting 25y.....go figure.
At any rate..I should have been more clear to begin with I apologize.
To me I think it's profound that on group1 it was 85-90 degrees with no wind and on group2 in was 60 degrees, wind some wind and one or two shots shot in drizzle.

This pic...top row only..was the the best ES and SD numbers of the first set which was 39g and 40.5.
From 39g..groups 1, 2 and 3 are 38.8, 39 and 39.2. Groups 4-7 are 40, 40.2, 40.4, and 40.6g.
The 2 dots in the middle are sighters the bottom row I was testing an EC tuner brake with 140 Berger hybrids over 37.7g Varget with BR4 primers. All the other groups are 144 Berger hybrids with H4350 and cci 450 primers...these are what I'm really testing.

This second set of groups was at 200y...I forgot to mention that.

 

[big5ifty]

This one I was doing a standard ladder test with the respective charge weights of the second test 38.2, 39, 39.2 40, 40.2, 40.4 and 40.6.

What are you testing for, and how are you testing for it ?

 

[Doom]

This one I was doing a standard ladder test with the respective charge weights of the second test 38.2, 39, 39.2 40, 40.2, 40.4 and 40.6.

On the second grouping test i marked the shots in each group 1, 2, 3, 5. These are the forth rounds of each charge weight. I had to do it this way because a couple of yahoos showed up at the range shooting AR's with varmit scopes and spotting scopes shooting 25y.....go figure.
At any rate..I should have been more clear to begin with I apologize.
To me I think it's profound that on group1 it was 85-90 degrees with no wind and on group2 in was 60 degrees, wind some wind and one or two shots shot in drizzle.

This second set of groups was at 200y...I forgot to mention that.

The target you posted in this post is what we call an Audette ladder and looking at it you would call 3 and 4 the loads you would refer to as a node. Typically those ladders are shot at 300 yds and can be shot at 200 yds although the results are typically not as clear. Being based on a single shot at 200yds there is the possibility that it is subject to random errors and shooter influence.

The Audette ladder needed 300 yds to work well but it requires a good shooter and begins to be influenced by ambient conditions, especially mirage. When Dan Newberry worked up the OCW concept he was looking for loads that shot well in most rifles, thinking of Federal Gold Metal Match in 308 as the goal. By shooting at 100yds he minimized the ambient effects of wind, mirage, temperature, lighting, etc.

@big5ifty has a unique take on the OCW method to find a node. In OCW we usually see the nodes at ~3% increments. It cuts down on the rounds needed. I actually work for 95% of max up after going up (1 shot) from min in 0.5 grain increments for pressure. With experience most of us will modify/simplify the process.

FWIW, looking back at you original post I see a node around 40gr. The second target with the bad group (#5) is shooter induced. Probably rear bag setup. If you are happy with that vetocity I would play with seating depth if you wish.

 

[Sixgun]

For an OCW test, you can ignore ES and SD.

Look for overlapping group centers with 3 incremental powder charges each roughly 1%. The middle one of the 3 is either where it's at or close to, and you can verify that by shooting it again with two groups 0.5% either side of it.



I think 40.2 . The three group centers 39.9 to 40.5 seem centered a smidge to the right of the 1 o'clock line and have what appears to be the same elevation.

It's a quick, easy and reliable verification test to reshoot 40.1, 40.2 and 40.3 and confirm you have overlapping group centers.

If you feel that 39 is the one, reshoot it next to 39.1 and 38.9, but 39.6 looks to me like or close to the scatter node, so the OCW node is either around 40.2 or 39.0 .

All you want to see is overlapping group centers. It's very easy to get emotionally attached to group sizes in an OCW test, but put your feelings aside and look purely for overlapping group centers.

The group size can be tweaked later with

Thinking back about it thats makes sense what you said about the group centers lining up. What do think the margin error should be?

 

[big5ifty]

Thinking back about it thats makes sense what you said about the group centers lining up. What do think the margin error should be?

I don't think there is a number you can put on that.

The way the test is done helps iron out the stats - round robin shots from each group after the barrel has cooled.

The problem with finding a good load is that it depends on being able to shoot a good load, otherwise you'll never be able to tell it's a good load by looking at the target.

Your three groups I mentioned previously center almost exactly in the same place.

If it was my target, I'd be confident with that result, and re-test 0.5% either side of the middle one.

I did just that with my 375 RUM this week, 0.5% either side of where I thought the node would be from my first test, and the +0.5% showed up better on the paper. That's why I believe in the OCW method, the results are repeatable.

 

[Sixgun]

For an OCW test, you can ignore ES and SD.

Look for overlapping group centers with 3 incremental powder charges each roughly 1%. The middle one of the 3 is either where it's at or close to, and you can verify that by shooting it again with two groups 0.5% either side of it.



I think 40.2 . The three group centers 39.9 to 40.5 seem centered a smidge to the right of the 1 o'clock line and have what appears to be the same elevation.

It's a quick, easy and reliable verification test to reshoot 40.1, 40.2 and 40.3 and confirm you have overlapping group centers.

If you feel that 39 is the one, reshoot it next to 39.1 and 38.9, but 39.6 looks to me like or close to the scatter node, so the OCW node is either around 40.2 or 39.0 .

All you want to see is overlapping group centers. It's very easy to get emotionally attached to group sizes in an OCW test, but put your feelings aside and look purely for overlapping group centers.

The group size can be tweaked later with seating depth changes.t

What are you testing for, and how are you testing for it ?

Im trying to find a node for a 6.5x47l with 144 berger hybrids with H4350 and cci 450's. I've been thinking this whole time 'look for the smallest ES and SD numbers' and that's your charge weight to use. After reading these posts in appears that not the way to go.
'RegionRat' posted an article from ARF.com earlier in this thread 'using the mean radius of say 8 five shot groups. It's a very interesting technique on finding a node. It's definately worth checking out. It's called the Accuracy Node Detection Technique.
Im gonna run my testing again using this technique but Im also gonna measure this target the way they described. This was done at 100y shot round robin. It's only three shot groups but im gonna measure it anyway just to get the hang of do the test. Everything written down pertains to the target starting at the top moving left to right...top left is 39g bottom right is 40.5g.

 

[Sixgun]

I don't think there is a number you can put on that.

The way the test is done helps iron out the stats - round robin shots from each group after the barrel has cooled.

The problem with finding a good load is that it depends on being able to shoot a good load, otherwise you'll never be able to tell it's a good load by looking at the target.

Your three groups I mentioned previously center almost exactly in the same place.

If it was my target, I'd be confident with that result, and re-test 0.5% either side of the middle one.

I did just that with my 375 RUM this week, 0.5% either side of where I thought the node would be from my first test, and the +0.5% showed up better on the paper. That's why I believe in the OCW method, the results are repeatable.

Thanks Fifty....Im also try it at 40.2 and see how does and compare that to the ANDT test from that ARF.com article.

 

[RegionRat]

I'm going to add a concept here at risk of sounding contradictory. We are trying to save shots, but we also need enough...
The less experience you have at load development and shooting, the more shots you should use to interpret a group node.

If you try to run the ANDT method, you would want no less than 5 shots per step. Calculating a mean radius on three shots is very risky business. YMMV

 

[Zero333]

The hell with ES-SD... I don't even take them seriously unless they represent 10 or more consecutive shots.

LET THE TARGET TELL THE TALE !!!

I've had hundreds of ES numbers around 1 or 2 fps in a 5 shot string... i sure as hell don't take them seriously.

Take at 10 shot string, and if ES is under 15 and SD in the single digits, that might be a different story.

TRUST THE TARGET AND REPEAT REPEAT REPEAT THE OUTCOME.

 

[Sixgun]

I will suggest this in the hope that it doesn't cause controversy or give offense to folks.

TLDR: with skinny short range data, study the shot impacts and groups, not the velocity stats.

There is no statistical strength in your SD/ES estimates, at least for the data you have shown. For the time being, focus on your target data and collect speed if you like but postpone making decisions on the velocity stats just yet.

Calculations of SD on three shot (or even 5 shot) groups is very unreliable and you are fine with just a study of the average and consider the ES, but even that ES isn't meaningful.

You can only use a 3 sample ES to reject a recipe, not to accept one.

If there was a hypothetical perfect shooter with a perfect gun, a giant ES could mean the recipe is a reject when it exceeds your goal standards, however, there is still the possibility that the giant ES was really the best charge and the loader screwed up on a single sample of the brass prep. So small samples of the load are very risky to judge, good or bad.

There is a leap of faith many of us take with the confidence we place in our brass prep. We also use the concept of smooth transitions and the idea that if we are taking fine charge steps it is unlikely that we would get a wild change in one step without seeing it on the neighboring charges. This is still risky.

Your math is correct, but the values have nearly a zero probability they represent an extrapolation that could be used to estimate the ES of a future sample.

For example, just because I run the calculation correctly, doesn't make those 3 sample SD values mean what they represent when there are say 30 samples.

That is not to say if you have a small sample with an ES of 30 versus one with an ES of 6, that the one with 30 is guarantied to be worse than the one with 6, but believe it or not there is still a possibility that with small samples the one with the ES of 6 can throw something larger than the 30 on the very next try and vice versa.

Now that I have made a negative comment on the SD of three shot samples, let me add that if you are forced to take risks on small sample sizes, consider using all of the bullet impacts to compare the group performance and then wait to make a stand on the velocity stats.

If you focus on what you think is a good charge weight and take many more samples of those, then the velocity data can begin to form a better average, ES and finally an SD once you have at least 15 or more samples, and more like 30.

To take risks on small sample sizes, it is best to stick with known pet load recipes in standardized guns. However, if you don't have that as a choice, I will suggest you analyze your target data the way that is shown in this link below.

By taking the impact position data of every shot in the group, and also in the adjacent powder steps, you build at least some probability that you can find the best charge (if there really is one).

https://www.ar15.com/forums/Armory/...-Accuracy-Node-Detection-Technique/42-524007/

The method requires you to analyze the target data and ignores velocity for the time being. It exploits every shot you take, but that also puts the burden of taking good shots on the shooter (all methods do.)

Once you take a decision risk on a charge weight, you should consider taking all the velocity data on it as well as nudge the charge up and down to investigate how well centered you are in the node.

BTW, there is still a possibility that the rig shoots the whole charge range roughly the same. It is entirely possible the gun produces temporary small groups in one test, and doesn't repeat the next, and then produces an equal group throughout the whole charge weight range when you aggregate all the data.

I know that upsets some folks, but the reality is that many rigs would shoot roughly the same no matter what they are fed especially when weather is factored in. That isn't necessarily a bad thing, but I know it upsets those who are being unrealistic about dispersion and statistics.

I hope you get the main point, which is to study the target and postpone the velocity stats as a pivot point on making decisions. In the end, when you take the testing to distance, if the velocity stats are good but the groups are not, those velocity stats are cold comfort. On the other hand, if you get good groups at max distance, then by definition those velocity stats are good enough. YMMV

Good Luck and have fun.

Thanks Region...I understand what you're saying now. That article from ARF.com is very interesting.

 

[Sixgun]

I'm going to add a concept here at risk of sounding contradictory. We are trying to save shots, but we also need enough...
The less experience you have at load development and shooting, the more shots you should use to interpret a group node.

If you try to run the ANDT method, you would want no less than 5 shots per step. Calculating a mean radius on three shots is very risky business. YMMV

I'll be using 5 shots when I do the test again when i can get back out. I just figured since i have this target i can practice on the procedure in analyzing the target actually going through the steps.

 

[big5ifty]

Im trying to find a node for a 6.5x47l with 144 berger hybrids with H4350 and cci 450's. I've been thinking this whole time 'look for the smallest ES and SD numbers' ...

Unless you're already at the node, velocity is not relevant other than as a safety check.

I started reloading for target rifles a few years ago, it's been a trial and error process. I took to Youtube, and found a couple of "pro" shooters advocating low ES over everything.

"Just get the lowest ES, then use seating depth or a tuner to tune the group size". Utter rubbish.

"Just use this brass, and this bullet, and you'll get ..." . Great info when those companies sponsor you, but not so useful for everyone else.

It doesn't really matter what method you use to get to a good load, you'll know it's a good load when the results repeat themselves on the target over and over.

Nothing more frustrating than coming away from the range with a bughole grouper, and going back at a different time with the same load and it's like the rifle has amnesia.

 

[Straightshooter1]

The hell with ES-SD... I don't even take them seriously unless they represent 10 or more consecutive shots.

LET THE TARGET TELL THE TALE !!!

I've had hundreds of ES numbers around 1 or 2 fps in a 5 shot string... i sure as hell don't take them seriously.

Take at 10 shot string, and if ES is under 15 and SD in the single digits, that might be a different story.

TRUST THE TARGET AND REPEAT REPEAT REPEAT THE OUTCOME.

Yup, it's all about what one can repeat and the target tells the tale and not necessarily just about the load, but the shooter as well.

Out of curiosity, I'm about to test a suggested powder I've heard about but not ever seen used in a 6.5 PRC. Here's how I collect data on my reloading:

 

[Zero333]

Yup, it's all about what one can repeat and the target tells the tale and not necessarily just about the load, but the shooter as well.

Out of curiosity, I'm about to test a suggested powder I've heard about but not ever seen used in a 6.5 PRC. Here's how I collect data on my reloading:

View attachment 1471806

H-4831sc is the hidden gem.

 

[CharlieNC]

Thinking back about it thats makes sense what you said about the group centers lining up. What do think the margin error should be?

I typically shoot a 2-shot ladder at 200yd which provides a much larger signal than 100yd. Using the center of the 2-shots I measure the vert and horz distance from the point of aim in mm, and plot the results vs charge weight. If you use small differences in charge across at least a 5% range the flat node will be obvious. Often the vert and horz correlate too.