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Thread: Fast vs. Slow powder

  1. #61
    Boolit Master on Heavens Range
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    Also, talking about electronics, pure tin solder is nothing but a time bomb. The tin grows wiskers that can easily cause shorts between close "wires" (within the board). Getting the lead out of solder is very counter productive, and causes built in absolence. Naturally, the consumer electronic folks love that. I have an old model IBM PC here that is still going strong after 12 years and not even a hint of a hiccup. Because of its slower speed and extreme reliability, I use it as my Ethernet server exclusively. It was built before that mandate to get rid of the lead. ... felix
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  2. #62
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    Quote Originally Posted by 45 2.1 View Post
    At least three of us have found what i've said to be true. Your methods and alloys may not be up to it though.
    Again, could you expand on the whats and hows involved. If there's a consistant way to do this, fill us in. I think the length of the is thread and responses indicate and interest and attempt at understanding all this. I don't care if it has to be spoonfed, I'm ok with that. I think this is worthwhile.

  3. #63
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    Bret4207,
    I have found that using Lee's hardness tester gizmo that if I test the surface of a bullet I will often get a 'harder' reading than if I file a flat into the core of the bullet. I've also found that the sprue end often gives a harder reading than the non sprue end. Could it be that the tin or what ever is causing the bullet to harden if 'floating' to the top ? Ya got me there !? I think once we get a way to measure things the world becomes a little more mysterious as we have to be objective rather than living in the comfort of our assumptions.... but I digress...
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  4. #64
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    The portion of the boolit that cools the fastest will be the hardest. The center of gravity spot will be the softest by default. ... felix
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    Felix,

    You'll get no argument here that the core of the bullet might be a few BNH point softer than the outer surface but while I might not have qualifications or experience of some here I've never had the core of a heat treated bullet retain the hardness of a comparable air cooled bullet while attaining any appreciable hardness to the surface. The only way to accomplish that that I know of would be by case hardening. Maybe someone found a way to do it and is keeping it a secret for whatever reason but I've never heard of it.

    It might be my methodolgy or alloy but WW seems to be the alloy of choice either straight or with tin, antimony, or shot added for heat treating and it's all I've used in it's various concoctions for years. Since I have both the Saeco and LBT tester at least I hope my testing equipment is up to snuff. Saying or assuming stuff is great and I have no problem with it but actual testing, especially when the tests are so easy, will give you the answer and this is something I've tested so feel I have a little background and knowledge about it.

  6. #66
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    Not to worry, Pat, as BA would say, let Mr. Gun be the microscope. Tracing what alloy does what on a numerical basis would be a nightmare come true. ... felix
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    Quote Originally Posted by felix View Post
    Not to worry, Pat, as BA would say, let Mr. Gun be the microscope. Tracing what alloy does what on a numerical basis would be a nightmare come true. ... felix
    Truer words were never spoken.

  8. #68
    Banned 45 2.1's Avatar
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    Quote Originally Posted by felix View Post
    The portion of the boolit that cools the fastest will be the hardest. The center of gravity spot will be the softest by default. ... felix
    This is a good place to start, with this statement which is very true BTW. I've managed to find that a boolit does indeed cool from the outside in by opening the blocks too soon. The first time showed a shell of the boolit which was solid and the core liquid. The outside was basically a consistent thickness. Alloy components play a great part here with antimony and arsenic being the two parts that will heat treat. The lead and tin will not heat treat. Hardness depends on freezing the lattice structure of antimony at a certain point with the quench temperature defineing just how hard it will be. Suppose that we have an alloy that has just enough antimony and arsenic to heat treat the boolit, then quench it. The outside of the boolit receives the full effect of the quench and will be harder than the center of the boolit. Also suppose that the inner temperature changes slowly enough that it doesn't heat treat due to very little antimony and arsenic in the mix, thereby being softer than its skin which insulates it from these changes in temperature. Quench temperature is very important when heat treating as a change of twenty degrees in boolit temperature effects hardness a lot.
    There you have my idea of what is going on. I've done this for several years and it continues to work. Some variation does occur due to diameter of the boolit. the larger the boolit the better in this. Loverin designs treat better also. 7mm boolits have caused somewhat less difference for me also. Anything from 30 caliber on up seem to work fine though.

  9. #69
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    I use one of Gussys Cabine Tree testers. The center of a boolit will always be a bit softer quenched or air cooled. Larger diameter boolits show more difference, little 25's almost no difference I can really measure. To me, this all makes sense.

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    If I can ask a question without this going sour how do you control the quench so the outer surface receives the full effect of the heat treat process while the core of the bullet cools slowly enough that it doesn't take effect?

    I'm trying to wrap my mind around this and it seems to me that if the alloy had the necessary ingredients to heat treat, no matter the amount, it'd heat treat the same as any other heat treatable mix.

  11. #71
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    [QUOTE=Pat I.;235566]If I can ask a question without this going sour how do you control the quench so the outer surface receives the full effect of the heat treat process while the core of the bullet cools slowly enough that it doesn't take effect?

    Ditto.

  12. #72
    Banned 45 2.1's Avatar
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    If I can ask a question without this going sour how do you control the quench so the outer surface receives the full effect of the heat treat process while the core of the bullet cools slowly enough that it doesn't take effect? Ditto.

    Casting temperature. Lower is better.

  13. #73
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    Gosh this a cracking education and read, another sticky perhaps.


    For fine firearms and shooting requisites visit my Web Site by clicking the link below:

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    This isn't to be argumentive but I'm on a fact finding mission here.Since it's fact that bullet temperature at quench has an effect on the final hardness of heat treated bullets what surface BNH do you consider taking "full effect of heat treating" while still keeping the core close to air cooled hardness? What percentage of what added to what are you using to add "just enough" antimony and arsenic? What temperature are you casting or setting the oven at to accomplish your idea. And finally what advantages have you found to having a bullet with a hard bearing surface and a dead soft core?

    I'm a bit of a heat treat junky and if there's a way and advantage to doing what you're talking about I'd like to learn it.

    This has certainly drifted away from the original topic hasn't it.

  15. #75
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    Quote Originally Posted by Pat I. View Post
    If I can ask a question without this going sour how do you control the quench so the outer surface receives the full effect of the heat treat process while the core of the bullet cools slowly enough that it doesn't take effect?

    I'm trying to wrap my mind around this and it seems to me that if the alloy had the necessary ingredients to heat treat, no matter the amount, it'd heat treat the same as any other heat treatable mix.
    Pat, I'm a complete idiot at times and the first to admit so, but reading all this I get the feeling that this is something which occurs naturally and to get a bullet hardened through and through would be the un natural event. Does this sound plausable?......

    In quenching, we are seeking to "capture" a matrix of the lead, antimony, tin structure. Achieved hardness depends on temperature differential. Since the outside of the bullet contacts the coolant first it experiences the greatest change in temp, at the same time, the inner core looses temp as well but the temperature differential isn't as great and the matrix is less fully aligned which creates a hard case/soft core condition. (hope that's well enough stated to convey the jist of my thought) If that is true, then the question may more appropriately be how can the depth of the hard case be controlled.

  16. #76
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    How deeply the hardness penetrates depends on three things:

    The rate of heat removal from the surface

    The rate of heat transfer from deeper parts to the surface

    The critical cooling rate necessary to achieve the full hardening effect of the quenching

    Steel and lead harden by different mechanisms when quenched, but still steel is a perfect analogy to explain how this works. Plain medium carbon steels very quickly convert from the austenitic crystal structure they assume at pre-quenching hardening temperatures when they're cooled. To get the steel cool enough to convert directly into the hard martensite state takes very swift cooling. A thin part will cool quickly enough when quenched to harden all the way through. But dunk a big red hot sledgehammer head in the quench bath, and though the water's vigorously boiling as it cools the surface layers, the heat has to be conducted out from the interior rather slowly through a considerable thickness of steel. By the time the center parts cool down to the temperature where hard martensite would form, it's already converted from austenite to pearlite or bainite and can't change to martensite. So you end up with a fairly thin hard surface layer, with the center softer and tougher. Chilling the surface faster with a brine solution and agitating it with jets will remove surface heat faster, but has relatively little effect on the depth of hardening because the heat can only be conducted so fast through the intervening layers. Add any of various alloying metals to the steel, and the formation of pearlite and bainite are slowed down so the metal can be cooled more slowly in an oil bath instead of water, and it will harden all the way through instead of just in a surface layer because it can reach the martensite start temperature without having already converted to other forms. Stress is reduced and the part is less likely to crack because the microstructural change is more uniform and more synchronous throughout the piece.

    With lead alloys, we're doing a similar thing in rapidly quenching the alloy from a temperature where the alloying elements are in solid solution, before they can crystallize out at higher temperatures. They crystallize very slowly at room temperature, and because the atoms diffuse slowly through the metal at low temperatures, the crystals formed are far smaller and more numerous than those formed at high temperature where the atoms are quite mobile. So the metal has to be chilled quite rapidly to prevent crystallization of the alloying elements. If the piece is big enough, in the interior some crystallization will have occurred before it can cool down and trap the elements in solid solution. Lead is a relatively slow conductor of heat. I don't know and have no idea where to find information on what elements slow down the early hot crystallization process in lead alloys. (If arsenic truly has a special effect as a "catalyst" for quench hardening, this is how it should work.) Cooling the quenching solution or agitating it can remove surface heat faster, but can't do too much to cool the interior faster because of the limited heat conduction. Theoretical cooling rates for the center of pieces of any given thickness can be calculated and result in pretty accurate estimates of the cooling rate. If we knew the "critical cooling rate" for the alloy, we could pretty well predict depth of hardening. That information isn't readily available for lead alloys, as it is for steels.

    And if you're using GOK alloy ("God Only Knows") as I usually am, there's no way of predicting this stuff. Melt it, cast it and shoot it works for me. I have found that with my soft scrap that contains some antimony (and probably some calcium, maybe a little cadmium as well since there's some cable sheathing and a little bit of battery grid in there) and little tin, I get pretty good hardness after quenching and aging at low alloy levels unlike what the Key to Metals article reported with an alloy that contained antimony with a good bit of tin. If antimony is ****** to quenched boolit alloys, tin is saltpeter.
    "A cheerful heart is good medicine."

  17. #77
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    Ric, that is about the plainest description I've ever read of the transition of steel microstructures in quenching/hardening. Thanks. It is a good thing that casting boolits from GOK metal is so forgiving, otherwise I'd still be stuffen my blunderbuss with rocks and glass shards.

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    Quote Originally Posted by JohnH View Post
    Pat, I'm a complete idiot at times and the first to admit so, but reading all this I get the feeling that this is something which occurs naturally and to get a bullet hardened through and through would be the un natural event. Does this sound plausable?......

    In quenching, we are seeking to "capture" a matrix of the lead, antimony, tin structure. Achieved hardness depends on temperature differential. Since the outside of the bullet contacts the coolant first it experiences the greatest change in temp, at the same time, the inner core looses temp as well but the temperature differential isn't as great and the matrix is less fully aligned which creates a hard case/soft core condition. (hope that's well enough stated to convey the jist of my thought) If that is true, then the question may more appropriately be how can the depth of the hard case be controlled.
    John,

    My post was directed to the statement that it was possible to control the HT and quench so the outer shell of a bullet would be the hardness of lino while the core would be at air cooled softness, whatever that may be since it wasn't explained. I'm no heat treat expert but if it's possible I've never seen or heard of it. I followed up this question with another which didn't get a response so have to assume it's not. If we were talking about WW that would be about a 9 or 10 BNH difference which ain't happening. I never said the core might not be a couple BNH points softer than the surface with bigger calibers, in fact I did, but the only way you could possibly get an air cooled soft core with a lino hard surface would be to figure out some method of case hardening.

    You have to realize we're talking about a thin short piece of material here soaked at relatively low temperature. You can drop quench a bullet from the mould and reach in and pick it up as soon as you can get your fingers around it without getting your fingers cooked. I wouldn't try that with a 1200 degree piece of steel the size of a sledgehammmer head.

    To be honest I don't even know why anyone who's HTed rifle bullets would question it. The only way I've found to test spitzer or roundnosed bullets is to file a flat on the tip of the bullet for the tester needle to sit. I don't get so freaked out about it that I have to file to an exact length so some might be .100 off the nose and some might be .250. It doesn't matter since they all read about the same, low to mid 30s for oven treated and high teens for dropped .30 cal WW with a little tin and shot mixed in. The easiest way to find out if the core is soft is to take a file to the bullet and test the BNH but I'll be damned surprised if you find a 10 BNH core and a lino hard surface.

    Pat
    Last edited by Pat I.; 10-30-2007 at 07:55 PM.

  19. #79
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    Quote Originally Posted by Pat I. View Post
    John,

    My post was directed to the statement that it was possible to control the HT and quench so the outer shell of a bullet would be the hardness of lino while the core would be at air cooled softness, whatever that may be since it wasn't explained. I'm no heat treat expert but if it's possible I've never seen or heard of it. Pat

    Pat,

    I can get a fair difference between inner and outer, but not with straight ACWW. It is easier to do with larger bores because of the poor heat transfer rate of lead. And it limits the top end hardness. The key for me is maintaining slightly less than 2% antimony content. Below 2%, the temperature at which you can get a mix to HT is very limited.

    With ACWW, I can water drop 44s and have them range 24 -28 BHN. 30s, go 28 to 35. Same mix, same pot temp, same batch. They will be hard through and through. I can take that mix and get an oven HT (@4% antimony) down to 400 degrees where 44s will now be 18 BHN and 30s still about 22 BHN. Great for HTing, but not worth much for soft centers.

    If I mix that ACWW 50/50 with pure lead, my 44s now water drop at 16 BHN. The center measures 9. My 30 s go about 22 BHN, but they are only about 20 inside. If I try to oven HT that same mix now at 400 degrees, I get now discernible HT as bullets will be 8 BHN in two weeks. Same as if I air cool. So the temperature reaction range is greatly reduced which is why the trapped heat in the center never hardens.

    So bottom line, you have to establish a mix with enough antimony to HT, but low enough to HT poorly to get the center soft. And in the end, it takes diameter and length to do it. Tin is another counter to HTing. The more tin, the worse the HT which is why lino and Lyman#2 don't HT as well as ACWW even though they have more antimony.
    Reading can provide limited education because only shooting provides YOUR answers as you tie everything together for THAT gun. The better the gun, the less you have to know / do & the more flexibility you have to achieve success.

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    Bass,

    Why doesn't this surprise me one bit, you're not getting any coaching from that other person are ya? That aside you've got me so I have to ask, what temperature are you casting at to get 28 to 35 BNH mould quenched WWs?

    This is what I think you wrote so correct me if I'm wrong. With mould quenched WWs 44s comes out 24-28 and 30s 28-35 and they're hard all the way through. Oven treat them at 400 degrees 44s are 18 and 30s are 22 and again they're hard all the way through. Except for the hardness you're saying you get, which I have to admit I don't believe, we agree as far as my knowledge allows since heat treating at 400 degrees would be a waste of gas or electricity to my mind.

    With the WW lead mix you get 22 BNH dropping 30 cal bullets (don't know but it could be possible) and a 20 BNH center. Last time I checked a couple and two were pretty close and I said that's a possibility already but in the real world you're not going to notice the difference. With the 45 what you said might be true but in the first place Lino isn't 16 BNH, which is what the other guy said you could get and I don't know if I believe you'd end up with a 9 BNH core anyway. 400 degrees isn't very hot for oven treating but if it's true your getting absolutely no benefits out of the treat I can't understand why if it'll harden when dropped.

    Obviously you have me in your sites which doesn't bother me too much but realize you're not going to get any medals by proving me wrong about something. If that was the case half the people I know would be walking around looking like General Patton. But also realize that while it's true I was born on a day it wasn't yesterday.

    Pat

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BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check