using a chrony to perform a ladder test?

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  • using a chrony to perform a ladder test?

    Hi Gents,

    I was wondering if there is actually a plateau in MV at each accuracy node on the ladder test and if so, can you then perform the ladder test using the chronograph to find the plateaus/ accuracy nodes only at short range?

    EDIT: sorry mods can you please move to the reloading section? done

  • #2
    Interesting question.

    In theory, yes.

    In reality, you sometimes get these really accurate loads that just have average ES/SD. I think this applies more to short to mid range loads.

    Long range loads, say for 1000 yards and beyond, will benefit from single digit ES/SD... It just makes vertical dispersion tighter.

    My answer to your questions is to run the ladder with the chrony at the same time. A good distance for a ladder is at least 500 yards. If your shooting for 1000, and can do a ladder at 1000, with the chrony... you're off to a good start

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      Thanks vman - I guess you're right, testing it is the only sensible answer - the problem is i dont think there are any 500 yard (let alone 1000) ranges around here where they let you test things. Unless you're allowed to at malabar? Might ask my club...

      otherwise 200 at Silverdale is the only other option

  • #3
    Originally posted by nuthead" post=20306
    Hi Gents,

    I was wondering if there is actually a plateau in MV at each accuracy node on the ladder test and if so, can you then perform the ladder test using the chronograph to find the plateaus/ accuracy nodes only at short range?
    You would have to do a test to be sure, but from what I've read, the answer is no.

    I read one article by an engineer who modeled the effects. If you ignored gravity (i.e. no bullet drop), what would happen is that as you increase velocity, the elevation goes up and down in a sinusoidal pattern. What these accuracy nodes are is just picking the point where you are at the crest or trough of these sine waves, as that means slight variations in velocity reflect a minor change in elevation, whereas, if you are in the middle, then a slight variation in velocity will get you the maximum change in elevation.

    This has something to do with barrel harmonics if I recall correctly, but if you have a heavy barrel, then the wave amplitude will be lessened, which is also desirable. More mass means that there's more energy required to vibrate the barrel, where energy from one cartridge is fixed, so more mass in the barrel means that there's less vibration. Stiffness gets erroneously mentioned sometime, that only changes the frequency of the vibration.

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      Originally posted by Mauser98" post=20639
      Originally posted by nuthead" post=20306
      Hi Gents,

      I was wondering if there is actually a plateau in MV at each accuracy node on the ladder test and if so, can you then perform the ladder test using the chronograph to find the plateaus/ accuracy nodes only at short range?
      You would have to do a test to be sure, but from what I've read, the answer is no.

      I read one article by an engineer who modeled the effects. If you ignored gravity (i.e. no bullet drop), what would happen is that as you increase velocity, the elevation goes up and down in a sinusoidal pattern. What these accuracy nodes are is just picking the point where you are at the crest or trough of these sine waves, as that means slight variations in velocity reflect a minor change in elevation, whereas, if you are in the middle, then a slight variation in velocity will get you the maximum change in elevation.

      This has something to do with barrel harmonics if I recall correctly, but if you have a heavy barrel, then the wave amplitude will be lessened, which is also desirable. More mass means that there's more energy required to vibrate the barrel, where energy from one cartridge is fixed, so more mass in the barrel means that there's less vibration. Stiffness gets erroneously mentioned sometime, that only changes the frequency of the vibration.
      Thanks for the tip mauser,

      I did some digging for the article you're referring to -is it this one?

      http://www.the-long-family.com/OBT_paper.htm

      sounds like the bore actually changes diameter (as well as whips) in a pulse that moves up and down several times before the bullet leaves the barrel which does something with the velocity? it sounds like every time the bullet passes through one of these points of constriction, pressure rises (as long as the powder charge is not completely burnt? But to be honest I think I have to sit down for a couple hours with a coffee before I have a chance of understanding what's going on!
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