Fine tuning using seating depth

Discussion in 'Reloading' started by ah141nj, Feb 20, 2010.

  1. ah141nj

    ah141nj

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    Ok, so I have been doing some load developement with various powders & bullets.

    I think I have a couple of promising loads.

    Seating depth/OAL is the final step for a pet load (from what I have been told)

    What increments should I start playing around in OAL?

    Do you start a maximum magazine length & just leave it there?

    Do you start at max OAL & work down in ? increments until minimum?

    The 2 loads I will be developing are...
    Varget with Hornady 55 gr FMJ's
    TAC with Nosler 69 gr HPBT

    They are both for an AR 16'' w/ 1/9
     
  2. jeffreybehr

    jeffreybehr

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    That's a Glock?
     

  3. Kentucky Jelly

    Kentucky Jelly

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    No but he is Reloading.

    In an AR you are going to be limited by the mag for OAL. Probably not going to be able to get close to the lands like you can with a bolt action. You can play with it a little bit, but I would worry more about reliable cycling.
     
  4. Poppa Bear

    Poppa Bear Protective G'pa CLM

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    Fine tuning OAL will not do any good if the load is not consistent to begin with. If the charge, bullet, case and powder stay very consistent for a given load, meaning that velocity is +/- 20 fps.

    If you are that consistent then start varying the charge weight for accuracy until you find that .1 grain increment that is most accurate. When you find that sweet spot you can start changing the OAL in .003 increments in both directions to refine that sweet spot because you will now be changing the pressure very slightly.

    The above advice is appropriate for someone looking to get that last .1 or even .05 reduction in their group size. This is much more accurate than I could ever shoot so I just find that OAL that loads consistently and shoots somewhat accurately.
     
  5. robin303

    robin303 Helicopter Nut

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    Measure some factory loads and start with an average.