Chrnograph question

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by teampete, Nov 11, 2011.

  1. teampete

    teampete Well-Known Member

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    Jan 17, 2011
    Hey everyone,

    I took my loads out today and chronoed them. Today was a very cloudy day and the instructions said on a cloudy day that there is no need to use the diffusers over the top of the chrono. So I tried to get reading from both.

    300 win mag, 210 berger vlds, 75gr H1000

    With the diffusers- My loads chronoed at 2851 and 2856

    Without the diffuers - my loads chronoed at 2879, 2881, 2898

    Which speed is more accurate?? on a cloudy day is it good to not use the diffusers? Please someone help me out here
     
  2. phorwath

    phorwath Well-Known Member

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    Apr 4, 2005
    I think you'll need more than 5 shots to demonstrate there's a proven difference between with the diffusers and without the diffusers. And I don't think there's an answer that will apply uniformly to all different brands and models of chronographs. In general, you shouldn't need to use the diffusers over the skyscreens with overcast skies. You should use the diffusers over the skyscreens on bluebird sunny days.

    Five shots with the diffusers on and 5 shots without the diffusers would be a whole lot better than 2 shots and 3 shots, to increase the confidence level that the diffusers are the cause for the difference in your recorded velocities. If the average of 5 shots was 30 fps faster or slower, with versus without diffusers, then I think you'd be on to something. The more often your demonstrate this difference going forward, the more credible your conclusion.
     
  3. Top Cat

    Top Cat Well-Known Member

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    Jul 6, 2005
    It shouldn't matter.

    A more important factor is the distance from the muzzle, and shielding the cables from muzzle blast.

    To insure the most consistent readings, I always use a minimum of 15 feet, but with some rifles a little more distance wouldn't hurt.

    TC
     
  4. papa45

    papa45 Well-Known Member

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    Feb 22, 2005
    Are the velocities you listed for five individual rounds, shown in the sequence fired? If so, your results may have nothing to do with diffusers. Typically, your velocities will increase as the barrel warms up. How long did you wait between shots?