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Thread: Powder charge variation and the Brazil Nut Effect

  1. #1
    Deadeye Dick Clusterfrack's Avatar
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    Powder charge variation and the Brazil Nut Effect

    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.

    Last edited by Clusterfrack; 05-10-2018 at 01:53 PM.
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  2. #2
    Member SecondsCount's Avatar
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    Wow! That is pretty interesting. I use WSF or Vit N320 and have never seen this issue but it is a good thing to watch for.
    -Seconds Count. Misses Don't-

  3. #3
    Deadeye Dick Clusterfrack's Avatar
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    Here’s a better picture:

    "You can never have too many knives." --Joe Ambercrombie
    Shabbat shalom, motherf***ers! --Mordechai Jefferson Carver

  4. #4
    Site Supporter
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    In 50 years of reading reloading materials, I'm seeing this occurrence for the first time. Good report!

  5. #5
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    It happens with loose tea leaves too. By the time I get to the bottom of a can of tea, the pieces are so small that it's essentially dust. I never considered the broader implications though. Good to know.

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  6. #6
    Member GuanoLoco's Avatar
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    I loaded a lot of PrimaV and had taken to shaking up each jug carefully, then manually throwing many priming charges.

    Looks like US availability is probably done, moving to CSB-1M next. If s like the ETR-7 / (I think CSB-1) from Expansion Industries (who went bust) but with a smaller flake. ETR-7 was my fav powder to date, and prelim testing shows CSB-1M is as good or better.
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  7. #7
    New Member H&KFanNC's Avatar
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    Very interesting and good information. Thank You!


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  8. #8
    Deadeye Dick Clusterfrack's Avatar
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    I was able to get quite a bit of Prima V, but availability has been intermittent. I like N320 as well, but it's expensive.

    Prima V feels really soft in comparison to Titegroup, and is not nearly as hot or dirty. The dynamics of my PrimaV load in my Shadows feels pretty close to perfect for me (e.g. 1.54s Bill Drill). I'm getting great accuracy as well. So, I'm going to continue to use it until it's gone. Hopefully, more will arrive from France...
    @GuanoLoco, where do you buy CSB-1M?
    "You can never have too many knives." --Joe Ambercrombie
    Shabbat shalom, motherf***ers! --Mordechai Jefferson Carver

  9. #9
    Member GuanoLoco's Avatar
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    Quote Originally Posted by Clusterfrack View Post
    I was able to get quite a bit of Prima V, but availability has been intermittent. I like N320 as well, but it's expensive.

    Prima V feels really soft in comparison to Titegroup, and is not nearly as hot or dirty. The dynamics of my PrimaV load in my Shadows feels pretty close to perfect for me (e.g. 1.54s Bill Drill). I'm getting great accuracy as well. So, I'm going to continue to use it until it's gone. Hopefully, more will arrive from France...
    @GuanoLoco, where do you buy CSB-1M?
    https://hi-techammo.com/products/csb...h-loading-data

    Owner is sitting on about 1000 lbs he wants to move; price is right. I’ll probably do a max order / hazmat fee soon and split with local friends.

    What I liked about CSB-1 / -1m vs. PrimaV - Cleaner, Meters much more consistently.
    Last edited by GuanoLoco; 05-11-2018 at 02:42 PM.
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  10. #10
    Deadeye Dick Clusterfrack's Avatar
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    How is the burn rate? Or perceived “softness”? N320 and Prima V feel softer to me than Titegroup.
    "You can never have too many knives." --Joe Ambercrombie
    Shabbat shalom, motherf***ers! --Mordechai Jefferson Carver

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