Evaluating shot dispersion on target

Discussion in 'Competition Shooting Forum' started by stray round, Aug 3, 2003.

  1. stray round

    stray round New Member

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    east tennessee
    This is my first post here. Could anyone help me with evaluating
    shot dispersion/placement when rifle shooting from position.

    I have used evaluating shot placement and relating it to common errors as a firearms instructor for handguns. And I've learned through much error of evaluating groups from the bench but I've never seen info for rifle shooting from position.

    Any help would be greatly appreciated!
  2. Smokin Guns

    Smokin Guns New Member

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    Hey stray round WELCOME!!!...I have no idea, Joe Haller does i know. Visit the other forums until someone shows up to let us both know!...;)
    Last edited: Aug 3, 2003
  3. inplanotx

    inplanotx New Member

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    Hi Stray Round and welcome to TFF. Glad to have you aboard and I'm sure Joe will be around to help in a little bit. Meanwhile, pull up a chair and chew the fat a lttile. Glad to have you aboard!
  4. stray round

    stray round New Member

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    Thanks for the reception guys!!

    I don't know that I'll be able to add much to the forum though.
    But you can bet I'll sure try to learn from the information being passed around.
  5. Joe Haller

    Joe Haller New Member

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    Shot Dispersion & Evaluation

    The only shot evaluation targets I have seen are for pistol shooting.

    I have not seen any of these target charts for position shooting or benchrest shooting. They may be out there, but I have not seen them.

    From what I know about position shooting with smallbore and highpower rifles: My best advice to my students, when I was coaching: “Learn to call your shots”.

    For benchrest where we are able to subract a lot of the human error: Vertical dispersion can be caused by the stock sticking on the sand bags and not moving back from recoil the same from shot to shot. We use baby powder or spray silicon on the bags to made the stock slide more uniform on the bags.

    Horizontal dispersion can be cause by WIND. And: Pressing the trigger to the side rather than straight to the rear.

    Dispersion on all directions can be causes by not managing the recoil EXACTLY the same from shot to shot.

    Barrel vibrations come in all sizes and all directions. They can give us horizontal or vertical groups. We can change those vibrations in centerfire rifles by changing powders, charging powder weight, changing primers and seating the bullet at different depths.

    In rimfire we don’t have as many options. We can calm the galloping vibrations by testing different brands of ammo until we find one that the barrel likes. AND: We can put an adjustable tuner on the muzzle of the barrel. Browning has a patent on tuners for centerfire. Buy a Browning or a Winchester if you want an adjustable BOSS tuner on your centerfire.

    In both rimfire and centerfire, free floating the barrel or putting upward pressure on the barrel at the forend can change barrel vibrations. We can also make changes in barrel vibrations by changing torque on the guard screws, or by gluing the action into the stock. Guard screw torque is measures in inch pounds. For glass bedded wood stocks, torque range should probably be between 15 and 30 inch pounds. More may crush the wood. For pillar bedded stocks you might go higher, but not more than about 40 to 45 inch pounds.

    These is a lot more to this subject, but I don't have the time this afternoon to write a book.

    Joe
    Last edited: Aug 8, 2003
  6. Smokin Guns

    Smokin Guns New Member

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    Thanks Joe!, Some of us are learnin' from you...[​IMG]
  7. stray round

    stray round New Member

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    Thanks for the feedback!!

    I had hoped there was something similar to the evaluation target for handguns. Once I found out about shot evaluation it really helped my handgunning. I could really use all the help I can get
    with a rifle too.

    I don't know about your guys but it seems as if progress is very incremental and little details are what is necessary for any advancement. It's great to get information from people who spend real trigger time instead of those gunshop gurus who abound.

    Once again thanks!!! And if you want to write a book I'm all ears.
  8. Joe Haller

    Joe Haller New Member

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    Location:
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    Here is a wind effect chart.

    I drew this chart up last winter. It explains some of those shots that make us say:"How did that happen?"

    With a right twist barrel, a 9 o'clock wind will drift the bullet to the right and DOWN.
    A 3 o'clock wind will drift the bullet to the left and UP.

    Attached Files:

  9. stray round

    stray round New Member

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    Well, I believe you may have just evaluated my target. LOL

    If you combined both of your target examples and place a tight group of remaining eight shots in the center you would have what I've been wrestling with. I knew the bullet would "walk" with the wind much as a spinning top is deflected by contact but I didnt think it would have as much practical affect.

    Guess I better start watching closer for those slight wind and wind switches. Thanks for all the help!!!
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