When doing load development what is a "node"?
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Dan Newberry's OCW Load Development System
Dan Newberry OCW or Optimal Charge Weight Load Development method or system for handloading, reloading, bullets, brass, powder, primers, accurate handloads.
optimalchargeweight.embarqspace.com
I am talking about a series of charges with a similar POI, as laid out in OCW. Although over the last few years it has come to be used in so many different ways, it is now a somewhat ambiguous term.
My understanding of a "node" is that barrels have vibration patterns like if you shook the end of a rope up and down and created "waves" in said rope. Ideally, you want your bullet to "uncork" from the crown of the muzzle as the barrel reaches its upper or lowest points in the wave form because the motion of the muzzle of the barrel has slowed to a stop before reversing direction. It matters not whether you choose the upper or lower point, just that the bullet exits the muzzle at that point every time. If the bullet uncorks anywhere in between, the barrel would be moving in any direction thus spraying a pattern rather than grouping. Please correct me if I have been led astray.
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While this is somewhat generally true, it's not always true for POI with a chronograph on there. OCW would be best to test POI similarities and chronograph would be best to test for MV similarities.
Both help to find accuracy nodes.
As you shoot different charge weights, you will normally notice that a certain range of charges will shoot noticeably more accurately than the others.
So... when the barrel fires a bullet there are lots of vibration waves being sent through the barrel, to the end and back many times before the fired bullet actually leaves the barrel.
https://www.varmintal.com/amode.htm read this a time or two and glom onto some of the broad stroke ideas, barrels move a lot in very small ways.
So what we are after is an optimal charge weight (OCW- dan newberry linked above) where those vibrations are repeatable from one shot to another and where small vibrations dont throw the bullet off unexpectedly. A "node" or a consistent part of that barrels vibration.
BUT we arent looking for a traditional mathematical node where the barrel is in the perfect center. Typically what ladder testing directly, and ocw indirectly, attempt to pattern is the results of the barrels vibrations on the bullets trajectory downrange.
If you find the point where the barrel is whipping up and down then you can identify a point where the faster bullets (which spend less total time in the barrel) are being released on the low end of the upswing and the slow bullets (which spend a tiny bit longer in the barrel) are released at the top. This way the slow ones are getting "throw upwards" so that their slower velocity is compensated for by the higher release point.
https://www.varmintal.com/amode.htm read this a time or two and glom onto some of the broad stroke ideas, barrels move a lot in very small ways.
So what we are after is an optimal charge weight (OCW- dan newberry linked above) where those vibrations are repeatable from one shot to another and where small vibrations dont throw the bullet off unexpectedly. A "node" or a consistent part of that barrels vibration.
BUT we arent looking for a traditional mathematical node where the barrel is in the perfect center. Typically what ladder testing directly, and ocw indirectly, attempt to pattern is the results of the barrels vibrations on the bullets trajectory downrange.
If you find the point where the barrel is whipping up and down then you can identify a point where the faster bullets (which spend less total time in the barrel) are being released on the low end of the upswing and the slow bullets (which spend a tiny bit longer in the barrel) are released at the top. This way the slow ones are getting "throw upwards" so that their slower velocity is compensated for by the higher release point.
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I think the neutral point in the sinus wave is where you want the bullet to leave the barrel. If it leaves anywhere else in the pattern it is unpredictable and like a water hose whipping around so it doesn't seem that would be the explanation of a node
So... when the barrel fires a bullet there are lots of vibration waves being sent through the barrel, to the end and back many times before the fired bullet actually leaves the barrel.
https://www.varmintal.com/amode.htm read this a time or two and glom onto some of the broad stroke ideas, barrels move a lot in very small ways.
So what we are after is an optimal charge weight (OCW- dan newberry linked above) where those vibrations are repeatable from one shot to another and where small vibrations dont throw the bullet off unexpectedly. A "node" or a consistent part of that barrels vibration.
BUT we arent looking for a traditional mathematical node where the barrel is in the perfect center. Typically what ladder testing directly, and ocw indirectly, attempt to pattern is the results of the barrels vibrations on the bullets trajectory downrange.
If you find the point where the barrel is whipping up and down then you can identify a point where the faster bullets (which spend less total time in the barrel) are being released on the low end of the upswing and the slow bullets (which spend a tiny bit longer in the barrel) are released at the top. This way the slow ones are getting "throw upwards" so that their slower velocity is compensated for by the higher release point.
Dan Newberry's OCW Load Development System
Dan Newberry OCW or Optimal Charge Weight Load Development method or system for handloading, reloading, bullets, brass, powder, primers, accurate handloads.
optimalchargeweight.embarqspace.com
You read and apply, because if you rely on people to spoon feed it to you, they will tell you how to do it wrong.
reading thru this makes me want to go back and check my loads again. Both my .308 and 6.5 loads shoot very well out to the ranges I have been able to shoot (out to 300yds). Recently found ranges close to allow me to shoot out to 800yrd. As I too thought that small groups at 100 would correlate to group sizes at 600. Maybe I can find a little better load for these distances? If anything it will give me more confidence in my loads.
If you know what you are looking for at 100, you’re fine.
It’s when guys don’t know what/how to look that they need the larger spread of longer groups to see the difference.
I do a node over 10 shots with .2 increases in powder charge. I look for a group of charges where the speed doesn't change all that much. Below is an example of a test I did. In this test, I would have loaded between 40.5 to 41.1 or 41.5 to 41.7. I think I did 41.6 on this, which was a 110 SMK. When shooting in hot weather, I load at the bottom of the node, taking into account pressure spike due to hot weather having an affect on the powder. In cold weather, I load a the top of the node if that makes any sense. Now whether this is the correct steps to find a node, I don't know. It just works for me and my rounds shoot best when I load in a certain powder charge range where the fps changes the least over several charges.
40.1 - 2935
40.3 - 2925
40.5 - 2960
40.7 - 2955
40.9 - 2967
41.1 - 2963
41.3 - 3003
41.5 - 3014
41.7- 3015
41.9 - 3026
40.1 - 2935
40.3 - 2925
40.5 - 2960
40.7 - 2955
40.9 - 2967
41.1 - 2963
41.3 - 3003
41.5 - 3014
41.7- 3015
41.9 - 3026
Read the link.above already posted. Explains everything and.how. dan newberry ocw
