First OCW Test

[lash]

Acoording to you, 45 grains is a scatter node. 44.3 is down 1.5% and it is an accuracy node. But going down another 1.5% gets you into another common accuracy node, so the pattern doesn't play out according to what you are saying.

You are not wrong, in that 44.6-ish is an accuracy node in many rifles. However, consider that the OCW method is nothing if not essentially a “tuning” method, similar to the past tuners used by competitive .22 match shooters to fine tune a barrel to optimal performance. It is dependent upon many things, such as barrel profile, length and harmonics. That means to us, that despite where most barrels are happy, not all barrels are happy in the same place. Thus the need at all for development processes like OCW, ladder and the Satterlee method. If it was all the same for every barrel, barrel length and barrel profile, then it would be published science.

I often tell people shooting .260 or 6.5 Creedmoor to look at 41.8-42.2g of H4350 as a solid moderate accuracy load. This is quite common and usually does the job, unless they have a lighter barrel profile or barrel shorter than 25”. Then it’s time to revisit the numbers and work up what works for them.

 

[Deleted member 113831]

You are not wrong, in that 44.6-ish is an accuracy node in many rifles. However, consider that the OCW method is nothing if not essentially a “tuning” method, similar to the past tuners used by competitive .22 match shooters to fine tune a barrel to optimal performance. It is dependent upon many things, such as barrel profile, length and harmonics. That means to us, that despite where most barrels are happy, not all barrels are happy in the same place. Thus the need at all for development processes like OCW, ladder and the Satterlee method. If it was all the same for every barrel, barrel length and barrel profile, then it would be published science.

I often tell people shooting .260 or 6.5 Creedmoor to look at 41.8-42.2g of H4350 as a solid moderate accuracy load. This is quite common and usually does the job, unless they have a lighter barrel profile or barrel shorter than 25”. Then it’s time to revisit the numbers and work up what works for them.

Exactly, that is why the idea of nodes being a certain set percentage apart is wishful thinking. Shoot the test, read the paper correctly, (this seems to be the hardest part) and you will find out what you need to know.

There is no unified theory of internal ballistics. There are recognized norms and general trends and that is about the best you can do from one rifle to another.

 

[Brentc]

Exactly, that is why the idea of nodes being a certain set percentage apart is wishful thinking.

You act like the percentages are something new. This is a basic concept from Newberry's OCW theory. I'm not making this stuff up. The percentages are used for prediction and they align with what's on the paper.

Honestly, how consistent do you think his load would be at 43.6 - 43.7 considering the POI change that follows shortly after? Applying OCW concepts to the target above, at 43.7 any atmospheric change that causes a rise in pressure will result in inconsistent POI. There's a node there, but it's not an accuracy node.

 

[Deleted member 113831]

You act like the percentages are something new. This is a basic concept from Newberry's OCW theory. I'm not making this stuff up. The percentages are used for prediction and they align with what's on the paper.

Honestly, how consistent do you think his load would be at 43.6 - 43.7 considering the POI change that follows shortly after? Applying OCW concepts to the target above, an atmospheric change that causes a rise in pressure will result in inconsistent POI. It's not an accuracy node.

I use percentages a lot. Newberry actually said that the scatter and accuracy nodes are 1% - 2% apart. I'm familiar with the site.

I said 43.5 - 43.7 was often a node with this combo, and I'll say again I have shot thousands of this exact combo. It is a well known combo to anyone who has shot 308 for any length of time.

Varget has an average gain of 0.35 fps per degree, so a 50 degree raise in temp would result in 17.5 fps change in average velocity.

Varget also averages 5 fps velocity change per 0.1 grain change in charge weight for this pressure range, so backing off to 43.5 from 44 grains would give 25 fps room before entering the high pressure area.

25 fps is more than 17.5 fps, so as long as you aren't shooting in temps more than 50*F hotter than the temp you developed the load at, you should have room to spare.

 

[Brentc]

I use percentages a lot. Newberry actually said that the scatter and accuracy nodes are 1% - 2% apart. I'm familiar with the site.

If you actually understand and you use the percentages a lot, why are you arguing about their usefulness in predicting the nodes?

Newberry will tell you the nodes are ~3% apart, which means the accuracy and scatter nodes are 1.5% apart. Again, it's a very basic OCW concept used to predict where nodes are.

I really don't doubt that you've seen 43.6 grains work well in other rifles. My responses are based on applying the basic OCW concepts to what's on the paper in the first post. Nothing more.

 

[Deleted member 113831]

If you actually understand and you use the percentages a lot, why are you arguing about their usefulness in predicting the nodes?

Newberry will tell you the nodes are ~3% apart, which means the accuracy and scatter nodes are 1.5% apart. Again, it's a very basic OCW concept used to predict where nodes are.

I really don't doubt that you've seen 43.6 grains work well in other rifles. My responses are based on applying the basic OCW concepts to what's on the paper in the first post. Nothing more.

You admit that 43.6 is an accuracy node, and you admit 44.3 is an accuracy node, and you say the paper shows 45 to be a scatter node.

What does the all knowing Dan Newberry say about two accuracy nodes being 1.5% apart?

You see 45 x .985 (1.5%) = 44.3.... 45 x .97 (3%) = 43.6

Accurate node (43.6 gr) + 1.5% = another Accurate node (44.3 gr) + 1.5% = Scatter node (45 gr)

I don't know how to break it down any simpler without drawing pictures.

AND....using the Dan Newberry method of node prediction would STILL result in choosing a smaller, less consistent high pressure node.... 44.3 grains in this combo is STILL a high pressure load.

 

[Brentc]

You admit that 43.6 is an accuracy node.

I don't know how to break it down any simpler without drawing pictures.

You are really hung up on something. Wow! I even agreed when you had the node at 44.3. And guess what you said the 42.5 to 43.7 is another node, I disagree that nodes are that large but I'll go with it on this instance. You drop your charge right in the middle of that range and you have your OCW at damn near 43, just like the calculation predicted.

The basic fundamental is that nodes are 3% apart.

Scatter node 45 x .97 = scatter node 43.6.
Accuracy node 44.3 x .97 = accuracy node 43

The picture drawn is the target. I never said 43.6 is the accuracy node here. It's obviously not on this instance.

The target says everything you need to know. It's right there in front of you. Yet you choose to ignore it because it's a node in other rifles. Keep on doing whatever mix up of a load development process that you choose to do, but ignoring the fundamentals of OCW tells me that you don't truly understand it.

 

[Deleted member 113831]

Keep on doing whatever mix up of a load development process that you choose to do, but ignoring the fundamentals of OCW tells me that you don't truly understand it.

That's some funny shit right there. I'm tapping out.

 

[CxAgent]

I appreciate the input from everyone. When looking at any target I post there is something to keep in mind. I am new to Reloading and new to slower fire shooting for precision. I am finding inconsistentsies in both. I loaded up more rounds and headed to the range. 43.1 through 43.9 and results did not match what I was expecting. I also made scope adjustments so I could not compare the latest round to the previous as point of impact changed. I called the
test inconclusive and threw out the
results. It will be a couple of weeks before I can get back to the Reloading Bench and range.