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Thread: BHN to much hardness?

  1. #21
    Boolit Grand Master



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    Quote Originally Posted by montana_charlie View Post
    The thing shown by the graph which impressed me the most was that when antimony and tin are equal in percentage, the alloy holds a very stable hardness over time.
    When the amount of antimony is greater than the tin, the hardness changes continuously, and perhaps randomly.

    If you have stored ammunition loaded with bullets that have a lesser quantity of tin, the hardness when they are shot will have little resemblance to what it was when loaded - or during any portion of the storage period.

    Yet, it is common to see advice where an alloy with 3 or 4 percent antimony is considered good when it only has '2% tin'.

    CM
    I think you've got that backwards Charlie. It's not more Sb than Sn, linotype has 12% Sb and 5% Sn and print shops (when it was still used) used it for years at a time without it becoming "too soft". Also many people use WW alloy at 2% Sb and 0.5% Sn without adding any additional Sn with excellent results whether air cooled, quenched or oven HT. When the Sn is a significantly higher than the percentage of Sb is when the amount of hardening is reduced and the amount of age softening is increased. More tin than antimony also creates "free" tin in the alloy which some believe can lead to leading though I'm not too sure about that. For many decades tin was the hardening agent of choice in Pb/Sn alloys and still is with the front stuffers. When Sb is added to the alloy is when the Sb/Sn is best when balanced, a very common practice in the metals industry.

    Rick
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  2. #22
    Boolit Grand Master
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    Apparently the chart Charlie posted is for non heat treated alloys, because even a COWW alloy heat treats way harder than these numbers.
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  3. #23
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    Quote Originally Posted by 454PB View Post
    Apparently the chart Charlie posted is for non heat treated alloys, because even a COWW alloy heat treats way harder than these numbers.
    Yes.
    The guy who did the testing, and those of us who would benefit from it, would never consider anything other than 'air cooled' bullets.


    Quote Originally Posted by cbrick View Post
    I think you've got that backwards Charlie. It's not more Sb than Sn, linotype has 12% Sb and 5% Sn and print shops (when it was still used) used it for years at a time without it becoming "too soft".
    Yeah, I didn't think you would be impressed by the 'stability' of an alloy that reaches a certain BHN ... then stays there 'forever'.

    CM
    Last edited by montana_charlie; 12-18-2014 at 03:05 PM.
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  4. #24
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    Quote Originally Posted by montana_charlie View Post
    Yes.
    The guy who did the testing, and those of us who would benefit from it, would never consider anything other than 'air cooled' bullets.

    Yeah, I didn't think you would be impressed by the 'stability' of an alloy that reaches a certain BHN ... then stays there 'forever'.

    CM
    Actually heat treating does have a valid place in a bullet casters tool box and alloys that don't have more tin than antimony will maintain useable hardness far longer than most will keep already cast bullets around.

    Impressed? One of the alloys in your chart is the vast majority of my casting and has been for many years. 2% Sb with 2% added tin air cooled, it's what I shoot in nearly every handgun and rifle I own. The only exception's are the high end 357 revolver match loads and possibly my new M1A. Low pressure HP rounds get 98/2 at about 7-8 BHN. Guess I don't understand what you mean by "impressed".

    Rick
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  5. #25
    Boolit Mold
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    Ya, thats what I hear and read all over, keep the tin lower than the antimony for a stable hardness, Im trying a few that way air cooled, then quenched. Im a little higher, strong 5% antimony with somewhere between 2 and 3% tin. Checking to see what happens and adjust from there. (14 hr after):
    K, was about 8 BHN 1 hr out of cast, and 10.4 after 14 hr. 14.3 BHN 1 hr after heat treat and 20.9 BHN after 14 hr. I have H4895 IMR4895 Accurate 2520 and other slower burning powder. Im leaning towards the IMR2520 but see what tomorrow brings for BHN, dont think it will change now, but will check, especially the air cooled, think that should change some. I think the 20.9 will deform enough to tumble with deer. Hey guys, any input will be very much appreciated. My M44's M38' slugged measure from .309 to .313 this cast is now at .311 weight is 179.6 to 179.8 sorry about the book, lol, but I need to understand each step as I go, not like loading BP rifle and the old 1858's Att a pic.
    Click image for larger version. 

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    Last edited by DanaDrew; 12-19-2014 at 11:13 AM. Reason: updated after 14 hr

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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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