Accuracy nodes

Discussion in 'Reloading' started by old_heli_logger, Jun 19, 2009.

  1. old_heli_logger

    old_heli_logger Well-Known Member

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    I read a lot about accuracy nodes. My understanding (and I could be way off base here) is that as soon as you pull the trigger the barrel starts oscillating (mostly vertical)…so here's my question: is the accuracy node achieved when the barrel is in the “up” position, the “down” position or “centered.” My guess would be either up or down, since these are the only two locations that the barrel is momentarily stopped. Maybe we can get the guys on Discovery’s Time Warp to do an episode on this...
    Thanks!
     
  2. boomtube

    boomtube Well-Known Member

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    You are largely right about the viberations, don't know as it's "mostly" any direction tho.

    Nor, in spite of some firmly held opinions, is there any way to say exactly where and how a given barrel is whipping for best accuracy; it's just not that clear. The vibrations are quite small, they start when the pin falls and continue while the bullet travels down the bore. The total time is very brief, the whole rife is moving and I don't think a soul on this planet has been able to watch what's happening so it's "best wild azz guess" work.

    Pick a position that sounds good to you and support it as strongly as you can while others pick another position with simular logic.

    Bottom line, it's interesting to talk about but it really doesn't matter. All we can do is try to find where it works best for our rifle(s).
     
    Last edited: Jun 19, 2009

  3. BillR

    BillR Well-Known Member

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    This sounds like the beginning of the Bill Calfie (SP) episodes from Benchrest central where he is trying to tell everyone that you need a barrel tuner and Varmint Al is telling everyone in graffic's how a barrel oscillates. Really got entertaining. :) Too bad the non experts all blew Bill out of the water every time he opened his mouth as it would of been interesting to see if Bill really could stop a barrel from vibrating and make it shoot bug holes with any load like he said could be done. He still has a few followers
     
  4. A/C Guy

    A/C Guy Well-Known Member

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    Nov 16, 2008
    The most accurate point is when the oscillation is in the center of the cycle.

    The theory is that you can shoot your various loads at identical targets. Overlap them/ superimpose the bullet holes and you should see a pattern of low and a pattern of high "misses". The load that groups in the center of the high and low groups in theory will be the most consistent load.

    The oscillations are rarely vertical and more likely to be at some angle. I have seen my loads shift POI from 7:30 to 1:30 on one rifle and 8:00 to 2:00 on another.

    The thread here on OCW and the related links to the websites of the frequency tuning of loads are very informative and I have found them to be rather accurate in their predictions using their methods of load development.