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Thread: Water quenching cast bullets

  1. #1
    Boolit Lady Reddot's Avatar
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    Water quenching cast bullets

    I have read that dropping your freshly cast bullets in a 5 gallon bucket of water will harden them significantly. However if you put them through a sizer this will decrease some of the hardness. Just what is being hardened in the quenching process? Just a thin outer layer of the bullet? I would think that the whole bullet would be hardened by this process.

  2. #2
    Boolit Master
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    Lead-antimony alloys with low to moderate amounts of antimony can be precipitation hardened. As they solidify the antimony becomes less soluble in lead, and precipitates out. Antimony precipitating into a matrix of solidified lead stresses the crystal matrix of the lead. The prestressed lead is harder than unstressed lead. Because lead is subject to creep, or stress-relaxation over time, the hardening process reverses itself very slowly.

    When you size a bullet the alloy has to flow into a new shape of smaller diameter. Depending on the amount of sizing and the bullet design, some of this deformation happens close to the surface, especially through lead flowing into the lube grooves. However the bullet also becomes longer - a process which deforms the alloy all the way to the center. Deforming prestressed lead relaxes the prestress and makes the bullet soft wherever it was deformed. So, if you just size a heat treated bullet without lubing it first, the deformation is concentrated close to the driving bands, which deform into the lube grooves. If you lube the bullet first, the lube grooves become just about incompressible and the deformation reaches deeper into the bullet. Thus heat treatment benefit is largely lost if you size the bullet after it has hardened. (But remember it takes days to weeks for the precipitation to occur after quenching, so you can lube after quenching so long as you do it within say 2 to 4 hours.)

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    Boolit Lady Reddot's Avatar
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    Grumpy, thank you for that answer.

    Does the hardening process start to reverse if you cast a bunch of bullets in the winter and don't use them for say a year? The reason I ask the question is I have access to a lot of lead now that may not be available in the future so I'm thinking that I should make hay while the sun shines so to speak.

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    Boolit Master Ricochet's Avatar
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    Smile

    They'll soften a bit, even in 6 months. Given enough time, they'd equilibrate at the same hardness as annealed boolits of the same alloy. But that'd take many years, I believe. I have a few quenched boolits I made in 2000 that are still quite hard.
    "A cheerful heart is good medicine."

  5. #5
    Boolit Master
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    Ricochet is right, as usual. Heat treated bullets harden fairly quickly for about two weeks, then continue to harden more slowly for additional weeks or months depending on the alloy. After perhaps a year they will be on their way toward softening, but this is a 'negatively accelerated exponential decay' process: even after quite a number of years they may still be measurably harder than annealed bullets made from the same alloy, though the softening will continue indefinitely.

    There is no reason to delay buying alloy, or even to delay casting bullets, over this re-softening issue. Simply heat treat your bullets a couple of weeks up to say a year before you shoot them. You can heat treat ten or twenty year old castings as effectively as you can new castings.

  6. #6
    Boolit Master
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    Other than a bit of oxide, lead dont rot! so you can accumulate as much as you have room to store. It can be stored either outdoors or inside. Further, there is no reason you have to cast/heat treat/size up whatever you get until you are ready to use it. Collect away and have fun!!
    R.D.M.

  7. #7
    Boolit Master


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    Lead is as cheap right now as it probably ever will be in the future. Beyond price the availability of lead may disappear in the not to distant future. More and more traditional uses for lead are being replaced either by other metals or plastics.
    With the Left Coast, weenies , and political thinking, spreading, it would be wise not to pass on any that you find while you still can.
    Even if you can't use all of your stash, it will trade for primer and powder to keep you shooting for a long time, kinda like a savings account for reloaders.

  8. #8
    Boolit Master

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    To answer your other question, I've hardness tested quenched boolits that were filed down 1/3 of their diameter, and they were just as hard inside as outside.
    You cannot discover new oceans unless you have the courage to lose sight of the shore

  9. #9
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    Quote Originally Posted by 454PB View Post
    To answer your other question, I've hardness tested quenched boolits that were filed down 1/3 of their diameter, and they were just as hard inside as outside.
    Me too with same results.

  10. #10
    Boolit Master
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    If technical discussions bore you, skip this post

    What hardens Lead when quenched is just that there are lots of incorrect Tin and perhaps Antimony atoms lost in the crystalographic latice of the Lead, plus some small islands of various precipitated compounds around the boundaries of or in Lead crystals. Both the incorrect atoms and the small islands of various Tin and Antimony compounds restrict deformation of the Lead lattice at room temperature. If quenched quickly, more of the incorrect atoms will be trapped in the lattice, and the islands will be small. The effect of aging on precipitates is for them to grow. My observation in the Lab 30 years ago was that over time, precipitate effect on resistance to deformation grew for a while until the precipitates reached an optimum size, then gradually fell off.

    The effect of rapid freezing should be strongest at the edges, and lesser in the interior of a casting, but I don't know how you would get at the interior of a casting to determine what the property gradient was, because of the Recrystalization effect I mention below.

    During the high temperature period of cooling right after freezing, those incorrect Tin and Antimony atoms migrate to Lead crystal boundaries. The incorrect Tin and Antimony atoms distort the Lead crystal lattice, and it is a lower energy state for them to be at the crystal boundaries.

    All the metals I am familiar with have some Recrystalization temperature at which they spontaneously reorganize their crystalographic lattice in order to reduce stresses in it. For purposes of Cold Work and elimination of the effects of Cold Work by Recrystalization, Lead acts as if is at high temperatures. That temperature for all the metals I am familiar with is about one-half of the melting temperature, expressed in degrees absolute: degrees Rankin or Kelvin. Lead and its alloys are about at that temperature when at room temperature. That which fuels the recrystalization is the stresses in the lattice. Supply any Cold Work, and the recrystalization should take off, and you will lose most of the effect of improper atoms, plus precipitates, plus cold work.

    There are other hardening mechanisms at work in many other metals when you quench them, such as in the Iron-Carbon system, but none of them are useful in Lead-Tin-Antimony.

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    Not bored but for sure lost. Could you give a Readers Digest version of what you just said in laymans terms?

  12. #12
    Boolit Master
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    Much is lost in doing so, but here's an effort at it.

    Lead freezes into a closely packed 3-dimensional pattern.
    Alloying elements, either through getting lost in the pattern or forming compounds, stress the pattern.
    Stressed patterns bend/stretch/twist/compress less easily.
    Metals patterns spontaneously reorganize at a temperature known as the Recrystallization temperature, and lose most stresses.
    The Recrystalization temperature for most Lead alloys is about room temperature.
    Cold Work of a metal at its Recrystalization temperature should make Recrystalization happen immediately.
    Other metals have hardening mechanisms that do not happen with Lead.

  13. #13
    Boolit Master


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    Basically, if you size hardened boolits you work soften the surface metal. this will only be the surface unless you are reducing the size a large amoumt. If you need hard surface boolits you must cast to size and water drop, or oven heat treat after sizing. The softening of the surface may not be as important as some think, considering that all the surface gets sized when fired. The internally hardened boolit stands up to the stresses of firing and even impacting the target, so all the benefits of hardening are not lost by sizing. You have to experiment and determine what process fits your needs. So far waterdropping, then sizing has met my needs

  14. #14
    Boolit Master mikenbarb's Avatar
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    Just store them in a smaller refrigerator and take out what you plan to use.LOL.
    Just my guess on keeping them consistent for a long time.
    ** Please bear with me for a day or two if I dont reply quickly.**
    Mike B.
    Gun Control= Being able to hit your target.

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    Boolit Master



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    Grumpy and NuJudge- OUTSTANDING POSTS!!! Thank you!
    [COLOR="Blue"]Yes, I am cynical, contrary, opinionated and cranky. So what? Nobody much liked John Adams or Howard Hughes either.

    We need to quit waiting for someone else to protect our rights. NRA isn't going to do it for us. If you aren't emailing, calling, writing and visiting your reps, if you aren't pro-active in this fight, if you just sit in front of the TV complaining about things then you're just as guilty as the anti gun crowd. If that makes you uncomfortable GOOD! Now do something about it, get active! MAKE A STAND NOW!!! "[/COLOR]

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