Weird ladder test...charges go up, impacts go down?

Discussion in 'Long Range Hunting & Shooting' started by odoylerules, Jul 28, 2018.

  1. odoylerules

    odoylerules Well-Known Member

    Dec 6, 2016
    1582AD4B-55A5-4304-96C4-C64E0CFCEAF7.jpeg F27F3975-A929-4543-81C6-8122E0245D2C.jpeg Shot a ladder/group test this morning...
    6.5 saum 24” #5 brux
    Hornady 6.5 gap brass
    140 Berger hunter hybrids
    Fed 215’s
    55° with light winds.
    Target at 650 yards, velocities with labradar. I Colored the bullet ogives and went to check and verify things at the target every 2 groups alternating colors. It was easy to see the color transfer so I am pretty certain of the groups/patterns.
    I think it’s just barrel harmonics, but I’ve never had this happen. I thought I read somewhere that’s not a good node to load when it does that? (Impacts way lower)
    The 59.0-59.5 looks good, and the 60.5-61.0. The 61.0 group is 1.5” across, that’s .23 MOA. The 61.5 group jumped way up, although one shot went super low. Could have been me, but you can see one of the rounds was way slower so that could be the reason.
    I feel like shooting it again to verify. Thoughts?
  2. Rhovee

    Rhovee Well-Known Member

    Jun 29, 2017
    It’s called positive compensation. Faster bullets hit lower. It has bench rest guys can have an es of 15 FPS but shoot way smaller groups then what should be according to ballistic apps. The window looks smaller for the 61 charge. I like the fact that 59-59.5 has same horizontal poi and velocity is pretty close.
  3. NW Hunter

    NW Hunter Well-Known Member

    Jan 29, 2010
    I way I see it, 61.0 is where your barrel harmonics are at rest.
    I notice that group is right in the middle of the other groups.
    The ES on 61.0 is 10 fps.
    I say shoot it again.
    If it impacts paper in the same spot and your ES and velocity are similar to the first time, that's a great load.
    Good shooting by the way!
  4. WildRose

    WildRose Well-Known Member

    Feb 3, 2011
    It has to do with your barrel harmonics which change with each charge.

    You look to be getting into a good zone between 60-61gr.
  5. odoylerules

    odoylerules Well-Known Member

    Dec 6, 2016
    I’m thinking I’ll shoot the same test next Thursday. It’s only 21 rounds total.
  6. rfurman24

    rfurman24 Well-Known Member

    Aug 29, 2010
    I personally would look at 59.2 or 59.3 and 60.5 +- .2. I would not run the 61 because 61.5 is a scatter node.