Why a diagonal target spread ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 4bycamper, Sep 6, 2009.

  1. 4bycamper

    4bycamper Well-Known Member

    Messages:
    607
    Joined:
    Apr 11, 2009
    This one has me wondering.
    Shooting my Winchester Featherweight 270 WSM, Acra glass bedded, 3x9 Leupold VX2 ER at the range. This bang stick shoots 0.8 moa regularly with H 1000 since bedding it. Started loading Magnum powder searching for higher velocity, seeking 3100 fps or better with 150 grain ABs, over CCI-200. This is something that H 1000 just won't do for me.

    My ladder has 5 round rungs one half grain apart from 68 to 72 grains.
    Results: 70.5 grains chrono's at 3130 av, 0.7 group.
    But what gets me is as I progressed from 68 to 72 grains, the groups walked diagonally up the target, from lower left to upper right, about 6 inches between groups. So I was constantly at my scope keeping my groups on the paper.

    So whats up with that, is my free floating barrel hitting the stock? Doesn't look like it but anything"s possible. Or maybe everybody has this going on ???

    Didn't mean to write a novel.
    This is the stick that may morph into a 28" HBAR for some serious fun.
    Thanks in advance.
     
  2. LouBoyd

    LouBoyd Well-Known Member

    Messages:
    770
    Joined:
    Oct 15, 2007
    What distance were you shooting? A possibility is that the wind was slowly changing direction or strength during the test.
     

  3. jimbires

    jimbires Well-Known Member

    Messages:
    923
    Joined:
    Mar 16, 2008
    all the shots with the same amount of powder shot into a group . then the next powder amount shot into another group . my lightweight rifles do this . I think it's just barrel harmonics . the barrel is at a different point in it's cycle when the bullet exits . when you find your powder load and set your scope you should be fine . Jim
     
  4. 4bycamper

    4bycamper Well-Known Member

    Messages:
    607
    Joined:
    Apr 11, 2009
    The target was at 100 yards.
    Barrel harmonics ? I guess that's the price of light weight barrels,

    Thanks guys.
     
  5. mo

    mo Well-Known Member

    Messages:
    432
    Joined:
    Mar 5, 2006
  6. 4bycamper

    4bycamper Well-Known Member

    Messages:
    607
    Joined:
    Apr 11, 2009
    OK

    I read it twice and I'm still chewing on it.
    The round robin testing i get, but the OCW ?
    I better sleep on it, again.


    Thanks
     
  7. jimbires

    jimbires Well-Known Member

    Messages:
    923
    Joined:
    Mar 16, 2008
    are you letting the barrel cool ? my light weight gets hot fast . Jim
     
  8. 4bycamper

    4bycamper Well-Known Member

    Messages:
    607
    Joined:
    Apr 11, 2009
    Cooling the barrel ? Yes, to cool to the touch. Every 3 or 4 shots.

    I am going to try the round robin method next trip to the range.
    So I'll give the barrel a cool minute or 2 between shots.

    Al