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Accuracy nodes?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 10:13
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I've read much lately about accuracy nodes. I was wanting to know more about them. If I happen to find an accuracy node with a certain bullet, say at 3050 fps, how wide can I expect that node to be? For example would that bullet still shoot well at 3000, and 3100, or only between say 3025, and 3075? Also if I should happen to load hotter than the accuracy node, how far do I have to go to hit the next one? Or maybe it's different for every rifle like everything else. Would the node be at about the same velocity for a different powder......or bullet? I'll leave it at that for now. I'm sure I can think of 100 more to ask, but I'll see where this gets me.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 13:31
Dale Clifford View Drop Down
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----when a long metal bar/rod is smacked with something like a hammer it creates a set of vibrations that oscillate back and forth , or the harmonics, in control systems this is called the impulse, (or Heavyside, or in some instances the Kronecker delta function) in signal processing it is called the Dirac function. Gun barrels have two or more sets of vibrations (the whack and longitudinal pressure wave inside the barrel) which makes them or gives the second order differential properties more like a Duffing system. The biggest plus to the duffing system is it has a semi-periodic nature leading to things called attractors or places were the system wants to be to remain stable.
accuracy nodes have been developed by the gun world to give somewhat of an account relating pressure, accuracy, extreme spread and standard deviation of the load date under the same roof for shooters. Here is a very interesting link concerning neck trimming, nodes and accuracy. Go to the pressure trace website for more information also
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 13:46
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Here is a decent article to get you started into it.  http://www.frfrogspad.com/loaddev.htm

If you join snipers paradise there is a user that goes by the name of Flea.  His name is Vern Harrison he runs Central Virginina Tactical.  Do searches for him and read all you can find when he talks about reloading and nodes.  He has like 5 world records and tons of shooting champion ships and is super willing to help shooters out with this stuff.  I PM him back and forth all the time with shooting and reloading questions, he knows a lot of stuff and loves to share his knowledge and experience.

Another guy that trains with Vern all the time is Mike Bandy, goes by the name Mbandy.  Search for his posts as well as he knows a ton too.

Ed Shell, goes by EShell has a lot of knowledge as well.


Edited by supertool73 - March/18/2009 at 13:48
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 17:02
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"..., how wide can I expect that node to be?"
 
The accuracy window, both for the charge and seating depth, varies by the rifle and any attempt to define it is foolish. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:23
Dale Clifford View Drop Down
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The node concept is taken from standing wave terminology when it crosses the x-axis and there fore the vibrations are at a min. Its old school barrel hamonics with a new twist according to the information put out by pressure trace. They also recognize that each gun and load is an individual entity, but have built a means of obtaining a measurements towards gaining a predictive edge by shortening the process of elimination of seating depth and powder wt.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:26
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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This would be much easier for me if Dale spoke english, or I wasn't so dumb.   Bucky
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:34
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Trigger all I can tell ya is that I... NODE... you were going to say that....LOL
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:35
Dale Clifford View Drop Down
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They are all just saying that the barrel will vibrate more resulting in less accuracy with certain combinations of bullets and powder (seating depth) . Some folks like crosswire are say each animal is different and need to test each time, other folks like pressure test are saying there has to be an easier way, and supertools folks who say they have all the answers worked out.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:53
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by rifle looney rifle looney wrote:

Trigger all I can tell ya is that I... NODE... you were going to say that....LOL
You really are looney!Big Smile
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/18/2009 at 21:55
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by Dale Clifford Dale Clifford wrote:

They are all just saying that the barrel will vibrate more resulting in less accuracy with certain combinations of bullets and powder (seating depth) . Some folks like crosswire are say each animal is different and need to test each time, other folks like pressure test are saying there has to be an easier way, and supertools folks who say they have all the answers worked out.
 
Well, I'm glad someone has it all worked out.................now if they could just tell me, "Hey trigger, your rifle will have 2 accuracy nodes, they will be about 200-300 fps apart, and be about 50fps wide, so get your loads in the middle of the one you want and kill deer" then I would be happy.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/19/2009 at 08:07
Dale Clifford View Drop Down
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Well, I'm glad someone has it all worked out.................now if they could just tell me, "Hey trigger, your rifle will have 2 accuracy nodes, they will be about 200-300 fps apart, and be about 50fps wide, so get your loads in the middle of the one you want and kill deer" then I would be happy.
 
That is exactly the case (except there is more than 2) the trick is at what powder level and seating depth..
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/19/2009 at 08:11
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so basicaly trigger.You have got to find the perfect swell,whip,twist the barrel likes with the bullet being used and your all good.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/19/2009 at 20:03
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Dale, would you recommend ladder loading, increasing charge weights a tenth at a time with the same seating depth, to find a range that produced the best groups with that seating depth?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/19/2009 at 20:45
Dale Clifford View Drop Down
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sure --  in a lot instances this is the only option open, especially with guns like ar15 ar 10 etc.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 05:32
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I've yet to see a good barrel,wearing a good crown and chamber,housed within a good and well bedded stock,boasting good rings/mounts/glass atop,not deliver the goods with concentric ammo.
 
That despite all notions of "nodes" and running the gamut from subsonic to primer curdling pressures. Kissing lands never don't hurt,nor does a propellant that boasts a smidge of compression at say 90% throttle.
 
I've bedded rifles with various forms of RVT silicone in their barrel channel,as a means of "node chasing",amongst other trevails(which was/is moot).
 
Bedding,throat/mag constraints always bear the most fruit,under the assumption all else is sound...........
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 05:38
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Let's not forget the break in...............(grin)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 08:15
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by Gyppo Logger Gyppo Logger wrote:

I've yet to see a good barrel,wearing a good crown and chamber,housed within a good and well bedded stock,boasting good rings/mounts/glass atop,not deliver the goods with concentric ammo.
 
 
How good is delivering the goods?  I can't say I have a bad shooting rifle, but I haven't seen the 1/2" groups yet either.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 09:18
Dale Clifford View Drop Down
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Originally posted by Gyppo Logger Gyppo Logger wrote:

I've yet to see a good barrel,wearing a good crown and chamber,housed within a good and well bedded stock,boasting good rings/mounts/glass atop,not deliver the goods with concentric ammo.
 
That despite all notions of "nodes" and running the gamut from subsonic to primer curdling pressures. Kissing lands never don't hurt,nor does a propellant that boasts a smidge of compression at say 90% throttle.
 
I've bedded rifles with various forms of RVT silicone in their barrel channel,as a means of "node chasing",amongst other trevails(which was/is moot).
 
Bedding,throat/mag constraints always bear the most fruit,under the assumption all else is sound...........
Your video on breaking in the Kimber is my favortie all time. especially if it had the "right" ring in the barrel yet.
 
just a question if you would--- what is your experience on barrel erosion amid all the things that is said/written.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 09:47
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Didn't work for me Dale.  Guess my ears are not sensitive enough to know when the harmonics are just right.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/20/2009 at 10:06
Dale Clifford View Drop Down
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saw a video one time where a guy had a tuning fork and he would tap the barrel at different places and put it up to his ear-- really funny.
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