Picking An Accuracy Node - Need Help Understanding

I do things differently. I load one round of each weight with the components that I'll be using in approximately 1% increments of the load as an increase value till I get to 5% over. Then I shoot each one, and stop when I see pressure signs. If there are rounds left over, I pull them, and back off from where the pressure signs started 1% and work backwards from there to find a load.

As I deal with my brass differently, I look for different pressure signs than most.
 
Trapper79 said:
Doing some testing for my Remmy '06 and had a question. I've watched countless videos and read pretty much all of 6mmbr.

I'm testing H4350 and 180 grain Speer BTSP. I started at book minimum and worked up to max in .3 grain increments. 3 shot groups of each.

Clearly I can see my groups start small, open up and then close in two separate occasions. Accuracy nodes - perfect.

This is where I need help. Some say just pick the best group and load for that. Others say the best choice is picking between the nodes and not the tightest group. If I pick between the nodes, my groups are not the best but from what I understand - these are my nodes my rifle likes? So confused! Need help!

Thanks!

~Trap
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Nothing wrong with your process so far.. If testing at 100yds, move to 200 or better 300yds... Now your test will be very clear on where the best node for accuracy is. Likely it will be the 2nd or higher load.

If you want to tweak, back off 0.2gr and work up on 0.1gr increments to 0.2gr past where you are now... But only test at 200yds and further. it will be very obvious what load will shoot best.

As long as the load is "safe" in your rifle, shoot multiple groups over multiple range days to ensure your result is consistent. Can ambient conditions affect your load? Yes, but if you are in the middle of your best node, it would require a wide swing in ambient conditions to change your result dramatically.

Assuming you are talking about a factory rifle and barrel, spend more time practising and enjoying the rifle then trying to tweak the last bit of performance Odds are you will see that your best load will still vary a bit in accuracy... that is just the nature of factory rifles.

Enjoy and don't overthink things too much... small groups on paper have answered your questions.

Jerry
 
burnaby said:
OP: Did you chrono the load? To find best ES/SD?

My preference is best single digit ES/SD, pref. near max load, then .1gr several over and under. Take best 5 shot group.
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I did chrono, yes. Started at 2700fps and very slowly climbed to 2800 mark. I'm still trying to figure out what ES/SD is
 
Mystic Precision said:
Nothing wrong with your process so far.. If testing at 100yds, move to 200 or better 300yds... Now your test will be very clear on where the best node for accuracy is. Likely it will be the 2nd or higher load.

If you want to tweak, back off 0.2gr and work up on 0.1gr increments to 0.2gr past where you are now... But only test at 200yds and further. it will be very obvious what load will shoot best.

As long as the load is "safe" in your rifle, shoot multiple groups over multiple range days to ensure your result is consistent. Can ambient conditions affect your load? Yes, but if you are in the middle of your best node, it would require a wide swing in ambient conditions to change your result dramatically.

Assuming you are talking about a factory rifle and barrel, spend more time practising and enjoying the rifle then trying to tweak the last bit of performance Odds are you will see that your best load will still vary a bit in accuracy... that is just the nature of factory rifles.

Enjoy and don't overthink things too much... small groups on paper have answered your questions.

Jerry
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Thanks Jerry :)
 
BCBRAD said:
Please elaborate.
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An "accuracy" node was dreamed up on the internet. It didn't exist before some writer on the internet thought of the idea. It is based on the fact that the barrel is in a state of vibration when a bullet is driven through it. But it is too variable to try and establish what happens at one particular oscillation.
Jack O'Connor's favourite saying was if you could see the barrel vibrating as the bullet went out, it would look like a wet spaghetti blowing in the breeze!
In short, no way could any one spot on it be recognized.
 
H4831 said:
An "accuracy" node was dreamed up on the internet. It didn't exist before some writer on the internet thought of the idea. It is based on the fact that the barrel is in a state of vibration when a bullet is driven through it. But it is too variable to try and establish what happens at one particular oscillation.
Jack O'Connor's favourite saying was if you could see the barrel vibrating as the bullet went out, it would look like a wet spaghetti blowing in the breeze!
In short, no way could any one spot on it be recognized.
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Silly question, but I need to clarify. The node or best accuracy is where I have my tightest groupings? I should reload around the my two tightest groups? Yes, I am ladder testing with 3 shot groups. I can clearly see my rounds group well, then climb eachother spacing about an inch or so and then group well again. Same with my higher loads. I see my groups side by side by an inch or so apart and then come back together to form a nice tight group. Like Jerry said; I think I may be over-thinking this whole test. In the end, all i want is a reliable 'hunting' round that is dependable to take a Whitetail or Bear within 100m.
All my testing is done at 100m. I don't really have access to any longer distances to practice at.

~Trap
 
H4831 said:
An "accuracy" node was dreamed up on the internet. It didn't exist before some writer on the internet thought of the idea. It is based on the fact that the barrel is in a state of vibration when a bullet is driven through it. But it is too variable to try and establish what happens at one particular oscillation.
Jack O'Connor's favourite saying was if you could see the barrel vibrating as the bullet went out, it would look like a wet spaghetti blowing in the breeze!
In short, no way could any one spot on it be recognized.
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Going to have to disagree on that one Bruce...... barrel vibration is pretty minimal and very repeatable...

If the spaghetti scenario were true you would never be able to sight in a rifle to the same point of impact....

https://m.youtube.com/watch?v=FaW_Hs0B79c
 
H4831 said:
An "accuracy" node was dreamed up on the internet. It didn't exist before some writer on the internet thought of the idea. It is based on the fact that the barrel is in a state of vibration when a bullet is driven through it. But it is too variable to try and establish what happens at one particular oscillation.
Jack O'Connor's favourite saying was if you could see the barrel vibrating as the bullet went out, it would look like a wet spaghetti blowing in the breeze!
In short, no way could any one spot on it be recognized.
Click to expand...


As in the video link posted by Superbrad the barrel does its 'whipping ' around after the bullet is long gone!

The energy pulse/vibration is an annular one that radiates from the source (cartridge being fired) to the end of the barrel and back to the source, depending on the material (type of steel) this is in the neighborhood of 18,000 ft/sec +/-.

So, if you could imagine a stone thrown in a lake of still water the energy from that radiates in all directions, now place a hollow steel tube over this picture and you will see waves of energy going out and reverberating back to the source, (basic physics).

In a barrel the energy wave deforms the barrel as it progress's out and reverberates back, the bullet passes through several zones of varying barrel diameter to its exit (muzzle).

The 'node' is when the barrel is at its least deformation, this been the ideal time for the bullet to exit.

The node is not from the barrel whipping around and seeking a calm spot but rather the annular pulse of energy that deforms the barrel,radially and along its length, as the energy is dissipated.

It is the timing of this event that will dictate where a 'node' is, therefore, the acceleration and velocity of the bullet most be accurately known, a computer program exists to help with the math.
 
A couple of generations ago the world class bench rest and long range shooters learned how to dampen the vibrations in the barrel to near non existence.
Why don't you read how they did it, in a book such as "The Accurate Rifle," by Warren Page?
 
I guess the idea, for me anyway, is not to eliminate barrel vibration but make it vibrate the same every time.

Good bedding, strong action ,secure fasteners and a free floated barrel aid in this.

As does all the attributes of bench rest ammo.

I have had good success doing it this way, that is tuning with powder charge to a node using an accurate chronograph (LabRadar) and a computer program (QuickLoad) to do the math.

This method makes good rifles (mechanically sound) better as far as accuracy is concerned.

The bonus here is that you don't have to fry a barrel seeking the best load, usually takes less than 10 rounds, 5 for an initial test to get the powder burn rate correct for the pressure produced and another 5 for a 5 shot group (usually at 300 or 400m) to verify.
 
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