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Thread: Working up a load?

  1. #1

    Working up a load?

    When working up a load, whats the favoured approach?

    Do you start at the lowest charge and put 3 rounds onto paper and monitor the grouping as the powder charge increases, then take the best powder weight and adjust the COL to tighten the group further ?

    or

    Work up your powder charge until maximum or you get pressure signs (not worrying about the group), and then adjust the COL to get a decent group from the charge?

    Does the second method always work? Is COL the fundamental variable in load grouping?

    Nathan

  2. #2
    I use Optimum Charge Weight system.
    Then adjust seating depth/COL.

    http://optimalchargeweight.embarqspace.com/#

    Probably not perfect, but systematic and it works for me.
    Personally I wouldn't go any further than the powder manufacturer's Max powder charge and certainly wouldn't work up the powder charge until I saw pressure signs, mainly because most pressure signs are quite fickle and open to misinterpretation. And also pressure can change depending on eg local temperature, so a load that is marginally safe on one day and be dangerous a few days later.
    I don't think that COL is the fundamental variable . . . in fact I don't think there's any such thing in reloading, it's much more a blend of factors.

    Triffid

    Triffid

  3. #3
    Quote Originally Posted by Triffid View Post
    I use Optimum Charge Weight system.
    Then adjust seating depth/COL.

    http://optimalchargeweight.embarqspace.com/#

    Probably not perfect, but systematic and it works for me.
    Personally I wouldn't go any further than the powder manufacturer's Max powder charge and certainly wouldn't work up the powder charge until I saw pressure signs, mainly because most pressure signs are quite fickle and open to misinterpretation. And also pressure can change depending on eg local temperature, so a load that is marginally safe on one day and be dangerous a few days later.
    I don't think that COL is the fundamental variable . . . in fact I don't think there's any such thing in reloading, it's much more a blend of factors.

    Triffid

    Triffid
    Apologies if this is a dumb question, but how do you find the optimal charge weight using the above method for your calibre and bullet?
    cheers
    Pasky

  4. #4
    It's a two stage process. Firstly you load 10 round with charges gradually approaching the maximum. Fire them checking carefully for any excess pressure signs (but see my reservations above!). This gives your maximum charge weight, or normally confirms that the powder manufacturers maximum is OK.

    Then you load six sets of four rounds at different charge weights starting from the Maximum you just established and reducing by 0.6% each time. Shoot these in sequence at a target to produce a group for each set of four. You can do this at 100 or 200m (or whatever range you like, unlike the Ladder test which is best shot at 300 or 400m).
    Measure your groups, including the offset of the group centre (MPI) from the aiming point. The OCW is the set in middle of the set of three which came closest to the same MPI.

    Sorry, I've probably not described it very well, but there's lots on the weblink I gave. There's also an Excel spreadsheet that you can used to calculate all the charges for you.


    http://ammoguide.com/myag/articles/d...Calculator.xls

    Triffid

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