Powder Charge increments in load development

Discussion in 'Reloading' started by txsendero, Jul 25, 2012.

  1. txsendero

    txsendero Well-Known Member

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    Is there any reason to test in smaller load increments than .5% during load development? In my case, I am referring to testing loads and calibers with charges of 60-70 grains, so .5% would be about .3 grains.
     
  2. J E Custom

    J E Custom Well-Known Member

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    I start load develoupment by starting with a load that is 2 grains below the listed Maximum.
    and work up in .5 grain increments (3 shot minimum) when I reach the most consistant group
    and/or SDs I load a range of rounds below and above the best test in .2grain increments
    to find the best that that load can produce.

    Also while testing in .5 grain increments if I start seeing pressure signs I list the max load for that batch
    as .5 grains under the pressure load in my log and dont exceed that in future test.

    I have found that some loads will improve with just .1 grain more or less, so after you get a load
    you like try .1 or .2 grain changes to home in on the best load.

    J E CUSTOM
     

  3. Clark

    Clark Well-Known Member

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    I work up in 1 gr increments in 7mm Rem Mag until I hit short brass life.
    Then I do another finer work up to find the exact threshold.
    Then I back off 4% powder charge, and that is my load.

    I work up in 0.1 gr increments in 32 S&W Long, until I get sticky cases.
    Then I back off 4% in powder charge, and there is my load.

    Everything else is in between.
     
  4. coues7

    coues7 Well-Known Member

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    Yep, what he said
     
  5. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    I walk a load up differently depending on if there is data for that powder or not. I have loaded hundreds of loads with mil-surp powder with ZERO load data out there for it, and I will start 10-15% below normal charges for similar burn rate powders, but walk up in a rather coarse 1-2% until I get near the wall.
    With powders with data, I start at 5% down or so, and shoot start, mid and top, and work around what shoots best. I don't screw around with .3 grain variations with a 100 grain volume case. You will wear your barrel out long before you get the thing shooting. Never start higher than 5% down unless the powder recomends it(like h110). And if there's data, don't go beyond book average unless you have a damn good reason(non-standard throat or non standard re-formed brass, etc.); by book average I mean just that, average high book charge or at least throw away the high charge load as an anomaly. Too many people load shop, get a bigger gun if you haven't got enough speed at normal pressure.
     
  6. Clark

    Clark Well-Known Member

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    I bought 32 pounds of surplus bulk IMR4895 all the same lot.
    It did not act like canister IMR4895.
    But after experimentation I realized it does have the same speed and density that H322 in the Quickload library has to within 1%.
    The threshold of loose primer pockets is then predictable for the 243, 257RAI, 260, 270, 308, and 8x57 with the same case head strength ~ 72 kpsi before subtracting margin.

    I got many pounds of Herters 164 with NO DATA.
    I assumed worst case it was fast pistol powder.
    I worked up a load in 35 Whelen, until I convinced myself it was comparable to Unique.
     
  7. Lefty7mmstw

    Lefty7mmstw Well-Known Member

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    Yep, once you know where the burn speed on mil-surp actually is, you can treat it nearly like canister. I still act with a bit more caution, though. I don't bother with loose pockets, though. Haven't gotten one in 5,000 shots or more. The last one was in a 270 and it was actually a book load with a 150. The rifle got hot before I got listed speed and within listed charge weights.
    I just got a m77 hawkeye in 35 whelen myself. It's using a 220 speer and rl15. My brother owned it before me, so I trust the data and probably won't change much, at least while I can get the speer 220.