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Thread: Powder charge variation and the Brazil Nut Effect

  1. #21
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    I'm also trying out wc244 winclean. It's basically 231 equivalent but cleaner(obviously). Midsouth is really promoting all the shooters world stuff right now. My chrono recently suit the bed, so I'm waiting on a magnetospeed to come in so I can do some serious load development.

  2. #22
    Member GuanoLoco's Avatar
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    I tested and ruled out Win231 and WST - both were (surprisingly) reverse temperature sensitive, as often claimed on the interwebs. I had always written that off as nonsense, but velocity swung pretty widely up with chilled mags and down with heated mags.
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  3. #23
    Hoplophilic doc SAWBONES's Avatar
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    I learned something new! Thank you.
    "Therefore, since the world has still... Much good, but much less good than ill,
    And while the sun and moon endure, Luck's a chance, but trouble's sure,
    I'd face it as a wise man would, And train for ill and not for good." -- A.E. Housman

  4. #24
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    Quote Originally Posted by Clusterfrack View Post
    I have been using Nobel Sport Prima V for minor power factor 9mm loads, and noticed some significant variation in charge weight (up to 1 grain in a 3.5 gr charge). At first, I thought it was just that the powder didn't meter well in the Dillon powder measure. But that wasn't the case. Charges were very consistent for 100's of rounds, but fluctuated up and down steadily.

    Inspection of the powder hopper revealed stratification of grain sizes, with the largest grains on top. This is a recently discovered phenomenon in the physics of granular media called the Brazil Nut Effect. Counterintuitively, the largest, heaviest particles end up on top. This is why rocks keep sprouting in plowed fields. Of course, powders with a very uniform grain size (e.g. Titegroup) wouldn't have this problem.

    My solution is to mix the powder with a chopstick when it's half used, and then again when I fill it. I also mix the powder in the jug before pouring. My charge weights have been spot on so far.

    Leave it to a scientist to "discover" what nut eating yahoo's have always known....
    A71593

  5. #25
    Quote Originally Posted by GuanoLoco View Post
    ACME has a pretty compelling bulk price for 124’s - $0.06 ea shipped for qty 12,000 (from memory). It is possible to do even better.

    Regular powders are usually $0.01 / charge, and N320 probably $0.02 / charge. Cheaper ammo = more ammo for practice, and that matters.
    Interesting, what do you do for primers?

  6. #26
    Member GuanoLoco's Avatar
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    Quote Originally Posted by mkmckinley View Post
    Interesting, what do you do for primers?
    This is getting a little far afield from OP, I get with competitive shooter friends and we do bulk orders (100K+) to drive down price and split.

    CCI’s for practice (cheaper and more available), Federals for match. I’ve mostly given up on the other primer manufacturers - too much variability / too hard / too many issues with availability, reliability, etc.

    I spring my guns to run CCI’s reliably in practice - also, I’m running a DA/SA gun (Tanfo Stock 2) so I don’t have a 1911/2011 that hits primers with the authority of Mjolnir. Anything that will light CCI’s with > 99.x% reliability will light Federals no problem.

    So...I can load practice 9mm for just under $0.08/ea, match for < $0.09 ea and that’s with range pick up brass.

    I have decided that brass picking may not be the best for my time/knees/back, so I bought a 55 gal drum of 9mm range pickup brass at about $0.01 ea. (Probably half going rate). Sometimes I trade brass for brass cleaning services - I have a cement mizer that will wet clean 5 gallons / 9000 cases at a time and a pair of 1000 watt dehydrators for drying.

    Powder - same thing. We go bulk, look for sales / discounts / shipping / hazmat, mazimize orders and split. My current practice only powder I conditionally took off someone’s hands at a stupid discount, worked up a load that I would never share but that has proven reliable and consistent at 126PF, and that costs me almost nothing (0.002 ea).

    The bulk deals from ACME on bullets are pretty good but it is possible to do a little better.

    A friend was asking the other day why I’m not negotiating and buying bullets in 100K+ qty and freighting it in. My normal buys are in the 10-30K range. It’s a good Q. I might do that next cycle.

    A different bullet manufacturer asked if I wanted to be a reseller - hard pass - I’m doing this as a hobby and don’t really want the hassle, even if doing so might reduce my costs further.

    I loaded and QC’d (case gauged) a couple thousand 9mm last night on the Mark 7/1050. Took a couple hours soup to nuts. Time is a thing too.

    Edit: I’m a little picky on reloading QC: COAL < 1.120, Crimp to 0.378”, CCI primers seated to 0.008”+, pass Ben Stoeger Hundo Case Gauge. 20 throw averages of powder usually within a few 10ths of a grain of my target, and I check at least before and after every load session, power factor > 125, and more like 128-133 for match ammo.
    Last edited by GuanoLoco; 05-14-2018 at 10:25 PM.
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  7. #27
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    WOW. You are serious about reloading.

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