Alloy Musings

Discussion in 'Alloys' started by Ole_270, Oct 3, 2017.

  1. Ole_270

    Ole_270 New Member

    I'm not sure I really understand all I have read on alloy makeup for our casting hobby.

    For this discussion, just assume we'll be staying under 1650fps velocity. The guns in use will be the following

    Marlin 336 rebored to 38-55, Accurate 38-250B, backyard gong at 1250 fps and deer hunting at 14-1600fps

    Marlin '94 25-20WCF, Noe 260283 plain base- plinking, backyard gong and small game. Mostly 1300 fps

    Marlin 30-30 for my young grandson. 165 Ranch Dog, practice and hunting



    Many posters insist on having equal Tin and Antimony percentages or close to it, with both fairly low percentages for expansion.

    Others, will tell you that lead/antimony alloy will flow well without the tin and that the equal percentage tin/antimony alloy will be more brittle than just the antimony or just tin added to lead.

    Now I'm wondering which way to jump?



    Where I'm at

    I've got two main home mixed alloys I use, both have been tested by BNE.

    1.3% SN, 2.1% SB, 96.6% PB Bhn=11 according to the calculator and pretty close by a Cabin Tree tester

    1.43% SN, 2.43% SB, 95.7% PB Bhn=12 by the calculator

    lots of Linotype, lead based Babbitt and some solder for mixing when I get my hands on more soft lead.



    The 2nd one water drops to 17-18 Bhn after PC in a 425 degree oven for 25 minutes and is what my grandson has been using.



    Now, I know both of these work in these rifles at the sedate velocities I normally run. I'm not really new to this, I shot my first deer with a home cast water dropped ww 31141 nearly 30 years ago and have taken several in the time since.



    If you had substantial quantities of these two alloys(not all that different anyway), would you cast bullets and ignore the detail chasers or start making changes?

    edit to add: WW+2%Sn mixed 50/50 with PB shows 1.24%SN, 1.49%SB,
     
    Last edited: Oct 3, 2017
  2. Brad

    Brad Moderator Staff Member

    I would use the alloys as is and never look back.
     
  3. fiver

    fiver Well-Known Member

    that's a little more tin then I generally use.
    but your close enough.
    use what you got.

    I recommend other alloy's for other uses but for what your doing there is no need to change anything.
    I wouldn't even bother upping the velocity for the 38-55 to go hunting, your already running right about where the round made it's reputation.
     
  4. Ian

    Ian Well-Known Member

    Just run it. Don't water drop them, or if you do, lower the powder coating oven temp to 375 or 400 for 2-3 minutes at the end of the burn just before quenching them and try to keep them from getting too hard. That's for proper bore obturation considerations, not expansion on game.

    At those speeds, expansion isn't really going to happen anyway unless using hollow point designs, so no worries about the way the alloy shears or smears, or doesn't shear or smear. You can disregard all discourse about keeping tin and antimony equal for your stated purposes, that's likely from people talking generalities or some other application entirely from yours.

    BTW, equal Sb/Sn in a basic ternary lead alloy has the effect of making the material very strong, very tough, and very malleable. When you cut the tin back from equal you start getting Pb/Sb lattices, which are large, planar dendrites that have a tendency to shear like a deck of cards sliding rather than just squish or stretch. In low Sb concentrations (2% or so) with even lower Sn ratio, the alloy appears very malleable but under high speed impacts will slip, shear, extrude, and tear, depending on the forces applied. Sometimes this is good for you, sometimes not, it just depends on what you're trying to accomplish. When the Sb is in higher percentage without enough tin to keep it all tied together, THAT is when antimonial alloy begins to become brittle like glass.

    ....and to your edit, I've used a LOT of 50/50 WW+2% Sn/pure, or the same thing made the other way, 50/50 + 1% Sn, and if I could only have ONE alloy to use for everything, that would probably be it even though it won't work for really high speed rifle bullets very well even at maximum heat treat.
     
  5. freebullet

    freebullet Well-Known Member

    Hunerd ways to skin a cat. I prefer to save the hard alloys for enrichment where needed. Only cause soft is easier to find here.
     
  6. Ole_270

    Ole_270 New Member

    Thanks guys, I was pretty sure I should just close my eyes and forge ahead with what I had.

    Just as a visual, here is a picture of some castings I pulled from my backstop, 2" dimension lumber, filled with ag lime(fine ground limestone). These were cast with a similar alloy, but untested. Bhn was somewhere around 12-14 if I remember right. Velocity of the 4 loads ranged from low of 1250, to a high of 1640fps.
    [​IMG]

    The 25-20 has been used over the last 30 years with everything from very soft to very hard alloys and 3 different molds. Velocities up to 2000 fps with the harder alloys. The gongs and small game don't seem to care which.
    Now I need some soft lead to make up an alloy for my 45 acp
     
  7. Ole_270

    Ole_270 New Member

    side view to see the amount of expansion better

    [​IMG]
     

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