How far apart are "nodes"

[stanley52]

With respect to powder charge and velocity, is there an average distance between accuracy nodes? Like 200 fps for example? I'm sure it must vary with barrel harmonics and caliber, but in general has anyone noticed a pattern? Just somethin I was pondering.

You need to read Dan's website about OCW. It works, and he very clearly spells out how to do it. Nodes are typically 3% (powder weight) apart from each other I believe he said. If he didn't say that on his website then he said it on snipers hide somewhere. Here's the link, read it and reap it's benefits.

OCW Overview - Dan Newberry's OCW Load Development System

 

[Bigeclipse]

You need to read Dan's website about OCW. It works, and he very clearly spells out how to do it. Nodes are typically 3% (powder weight) apart from each other I believe he said. If he didn't say that on his website then he said it on snipers hide somewhere. Here's the link, read it and reap it's benefits.

OCW Overview - Dan Newberry's OCW Load Development System

I assume this means everything else in the equation being equal...seating depth, brass, primers...etc? I will test this tomorrow.

I just worked up a load that is accurate at max charge...so in theory, I should be able to back off ~3% powder charge and expect similar accuracy...my current load is right at 52 grains so 3% of that is 1.56 grains making my test load 50.44 grains.

Also, worth noting to everyone else...this is a picky rifle and the accuracy between nodes has been significantly different...ranges from 4MOA down to ~.6MOA with simply changing powder amount and nothing else so I should be able to see immediately if this holds true (for my current load/rifle that is).

 

[stanley52]

If you follow his instructions on performing a proper OCW test, then yes, you SHOULD find another node around there. Please let us know what you find!

How you can test to see if you truly have a stable load I.E. The POI does not shift with temperature and SLIGHT variants in powder charges (from miss throws) or from different powder lot numbers. An OCW test is not necessarily trying to find the most accurate load, you are trying to find the most repeatable/stable load and then you adjust seating depth to tighten groups after you find your stable load. So just because you have an accurate load, that does not necessarily mean that is a "node" by the OCW method; although, most nodes are significantly more accurate than the scatter groups will be. His website spells it all out and what it's purpose is.

 

[Bigeclipse]

If you follow his instructions on performing a proper OCW test, then yes, you SHOULD find another node around there. Please let us know what you find!

How you can test to see if you truly have a stable load I.E. The POI does not shift with temperature and SLIGHT variants in powder charges (from miss throws) or from different powder lot numbers. An OCW test is not necessarily trying to find the most accurate load, you are trying to find the most repeatable/stable load and then you adjust seating depth to tighten groups after you find your stable load. So just because you have an accurate load, that does not necessarily mean that is a "node" by the OCW method; although, most nodes are significantly more accurate than the scatter groups will be. His website spells it all out and what it's purpose is.

hmm interesting...then I am not sure if I am in an accuracy node or not. What I did for my current load was I first tested pressure up to maximum. Once all loads passed this test...I then loaded 3 rounds every .5 grains in powder charge. I started with the middle of the load chart and worked up to max loads. which was 49.5 grains, then 50, 50.5, 51, 51.5 and finally 52 all at the same seating depth of .050 off lands. FYI...I use a trickle throw for every load when it comes to my rifle ammo so feel very confident in powder accuracy. I then picked the two best groups, which was 50 grains and 52 grains. 50 Grains was actually better than 52 grains. The 50gr load was about .9MOA and the 52 grain load was about 1.25MOA. I was very happy with the speed of the 52 load so I started with that one for messing with seating depth. I went .040 and .060 off lands for next two groups. .040 got worse while .060 got better which means my rifle with this load actually likes the bullets further off the lands for whatever reason. I then loaded another set of 3 at .070 off the lands which got even better and is my current load which resulted in about .6MOA so technically my rifle could get even better...to be fair I simply just called this "good enough" because this is a hunting rifle for deer out to 400 yards and I was running out of accubonds. I have about 25 left and cannot find anymore as of yet so I was saving these 25 for hunting season but do not mind using 3-5 more to test this theory.

 

[stanley52]

Realistically you would need 18-21 to do a base test. For a .308 you typically go by increments of .3gr (if I remember correctly), through a range of 6 or 7 different loads. You shoot one round of each powder charge at it's on target on through all charges, then do it again for the second round for all charges, and then for the 3rd shot of all charges, letting your rifle cool between EACH shot. The purpose of this is to evenly distribute wind conditions, heat, and bore fouling across all groups. You then take the 2 or 3 groups which will be consecutive that have very close to the same point of impact. Select the charge that is right in the middle. So if I had 40gr, 40.3gr, 40.6gr as my most consistent groups, then 40.3gr should be my optimal charge weight. You can test this group by adding 1% to the powder charge and subtracting 1% from the powder charge to make sure you have a stable charge weight (I.E. The POI should not shift with +/- 1% of powder. If you have a stable load, then you adjust seating depth to fix accuracy.

 

[Unofficial Gun Addict (UGA)]

With respect to powder charge and velocity, is there an average distance between accuracy nodes? Like 200 fps for example? I'm sure it must vary with barrel harmonics and caliber, but in general has anyone noticed a pattern? Just somethin I was pondering.

This was the OPs original question. OCW to me seems to be another way of load testing, as opposed to node prediction. The two are completely different in theory and application. With enough rounds tested through various powder ranges on a given rifle, node distance could theoretically be mapped out as long as numerous nodes fell within the given powder/pressure range of the rifle in question. However, taking this information and attempting to apply it to another rifle seems like wishful thinking. OCW makes sense to me though I have not verified as my methodology seems to work, so no motivation to change, yet.

On the other hand, trying to use variables to estimate node distance without even shooting the rifle, to come up with accurate powder charges, in my opinion, is sheer fantasy. Just too many factors for a person to account for. Barrelracers assertion that barrel time and length can be used to accurately predict nodes is too simplistic for such a complex issue. As I said earlier... If it was that easy, everybody would use it.

 

[Mikecr]

There are only anecdotal trends, and they present in an abstract.
As a community, we haven't even managed to hammer out a logical load development method..
So while we bicker about OBT, OCW, Ladders, etc, the question of node separation stands unknown.
It is unknown.

In fact, nobody knows what a 'node' actually is. We don't know what 'tune' is. We don't know what seating, or primer striking are doing. Many of us have completely different notions about these things, and none of us know.

 

[stanley52]

This was the OPs original question. OCW to me seems to be another way of load testing, as opposed to node prediction. The two are completely different in theory and application. With enough rounds tested through various powder ranges on a given rifle, node distance could theoretically be mapped out as long as numerous nodes fell within the given powder/pressure range of the rifle in question. However, taking this information and attempting to apply it to another rifle seems like wishful thinking. OCW makes sense to me though I have not verified as my methodology seems to work, so no motivation to change, yet.

On the other hand, trying to use variables to estimate node distance without even shooting the rifle, to come up with accurate powder charges, in my opinion, is sheer fantasy. Just too many factors for a person to account for. Barrelracers assertion that barrel time and length can be used to accurately predict nodes is too simplistic for such a complex issue. As I said earlier... If it was that easy, everybody would use it.

I know what the original question was about, if you read about OCW you can somewhat predict where nodes are, but to do that you really need to go through the whole method. Go to Dan's website and read. I say again, you can generally predict other nodes, if you CORRECTLY do an OCW tests to begin with. This is my point with OCW in relation to the OP

 

[Unofficial Gun Addict (UGA)]

Stanley52... Please don't take offense as I was not challenging your belief that OCW allows you to predict where nodes are on your rifle. What I was attempting to convey is that OCW appears to be another method of load development, whereby one is trying to find a node that with all other variables being the same, gives a wider margin for powder/velocity variances while still keeping the point of impact from changing dramatically.

My concern was with Barrelracers conviction and more specifically, his assertion that others should not comment with respect to node prediction based on barrel time and length, as they had no real world experience with which to reply, but that he did have real world experience so his opinion was basically the only one that the OP should listen to... and everyone else should shut up.

I'm always open to new ideas and hoped that he would reply with his methodology, because if it seemed sound... I would put it to the test. I was not overly optimistic that either he would... And if he did... That it would be sound. I sure as hell have never thought of myself as knowing everything.... And one reason I love this site is because members help me to broaden my knowledge base... And give good suggestions i had not thought of.

I'm open to trying Barrelracers theory if he would be willing to post his methods, however, in my mind, those 2 variables alone (barrel time and length) seem much to simplistic to predict nodes. Node prediction to me sounds a bit like the holy grail. I'm not saying it doesn't exist, I'm just saying that I think it would take a hell of an adventure to find it, and more time, money, and labor than most men are willing to commit.

 

[Mikecr]

if you read about OCW you can somewhat predict where nodes are, but to do that you really need to go through the whole method.

You're suggesting that if you run through the OCW course, you could then look back and makes sense of it(as somewhat predictable). I suspect folks have been doing the same with OBT.

The TRUTH(until proven otherwise) is that you never could PREDICT nodes using OCW, or any other method.
You're simply assigning meaning to an abstract, without verifying that it passes all tests, including blind testing/prediction. This is more faith, or delusion, than credible reasoning.

 

[stanley52]

You're suggesting that if you run through the OCW course, you could then look back and makes sense of it(as somewhat predictable). I suspect folks have been doing the same with OBT.

The TRUTH(until proven otherwise) is that you never could PREDICT nodes using OCW, or any other method.
You're simply assigning meaning to an abstract, without verifying that it passes all tests, including blind testing/prediction. This is more faith, or delusion, than credible reasoning.

I'm sure you know more than I, and I am not being sarcastic. I know it has worked for me, I know it has worked for many of my friends, and many on the hide. Nothing is definitive till you actually test it, yes this is correct; however, there is methodology, and though it might not work all the time.. There's enough times it does work for you to take a second look, or maybe use it as a starting point.

 

[Barrelnut]

There are only anecdotal trends, and they present in an abstract.
As a community, we haven't even managed to hammer out a logical load development method..
So while we bicker about OBT, OCW, Ladders, etc, the question of node separation stands unknown.
It is unknown.

In fact, nobody knows what a 'node' actually is. We don't know what 'tune' is. We don't know what seating, or primer striking are doing. Many of us have completely different notions about these things, and none of us know.

This is saying a lot from a guy who does actually know a lot about this hobby. LOL

 

[captacademy]

Very interesting!

 

[Mikecr]

Well, I for sure would want new ideas to work. I use QuickLoad, and somewhere around here I have an OBT spreadsheet that graphs, and it graphs predictons as well. No doubt I was among the first reloaders who really reached for it. That's the problem -I was reaching. I was assigning correlations to every load in view.
But honestly, where rubber hit the road it wouldn't predict diddly squat..

I have a PowerBall spreadsheet that does as much for me. Very h-tech, neural net, math self-adjusted with self-testing over past 1,000 and 100 drawings. You gotta know I reached for this to be right. But the truth is it never will be.
Most major universities attempt to predict lottos, and/or the DOW.. Expensive supercomputer time, on someone else's dime..
But they never have bettered their random control standards, as from any point the unknown remains 50/50.
The unknown is what you have to get beyond first, and this isn't possible with truly random situations. Much as we want otherwise..