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Bi-metal bullets; barrel wear?

Discussion in 'Rifle Country' started by A strange person, Jun 25, 2012.

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  1. A strange person

    A strange person Member

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    Are bi-metal bullets any worse for barrels than normal copper-jacketed bullets? I know someone started a thread on this a while ago, but it didn't really get alot of responses.
     
  2. Hacker15E

    Hacker15E Member

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    I haven't seen any actual evidence ever presented that bi-metal is any significantly harsher on a bore than copper jacketed.
     
  3. Deus Machina

    Deus Machina Member

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    On a purely technical sense... probably.
    Will you notice the difference in your--or your grandchildren's--lifetime? Probably not.
     
  4. adelbridge

    adelbridge Member

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    Technically copper/lead bullets are bi metal. I have been worried about steel jacketed bullets but logically if they have a similar POI as copper jacketed bullets they would approximate copper wear on your barrel.
     
  5. JohnBT

    JohnBT Member

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    The bimetal bullets - advertised as bimetal - I have seen and read about do not have any steel in them. They are lead cores covered with iron and then with thin copper. Iron is an element and is relatively soft.

    Someone actually ran some Swiss 9mm bimetal through a lab test. Here are the results. I was looking at this ammo because a P210 shooter from Switzerland highly recommended it and J&G was selling it for $10/box by the case. I bought a few. After shooting the first case, heck the first box, I knew he was right. A little hot, clean and accurate.

    ______________________

    9mm GECO 124Gr FMJ. Swiss RUAG Mfg.

    Fe = iron
    Cu = copper
    Pb = lead
    __________________

    Results

    Jacket wt.-18.32grains
    Core wt.-105.422grains

    Jacket
    4.83% Cu (plating)
    94.6% Fe
    .63% traces of Zn, Pb, Bi, Ni, Cr, Al

    Core
    98.65% Pb
    1.3% Cu
    <.05% Al, Fe, Bi, Zn

    Samples run on ICP-OES in aqueous acid solution (digestion), 10% Aqua Regia by volume.

    Yes, 95% Iron jacket (not steel) with a 5% copper plating. Core is lead.

    ______________________
     
  6. 243winxb

    243winxb Member

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    Hornady GMX® (Gilding Metal eXpanding) same as bullet jacket at 95% copper & 5% zinc. No lead. http://www.hornady.com/store/GMX-Gilding-Metal-eXpanding/ The land in the barrel is about .004" tall, this is what gets the most wear. Not the groove, because grooves are the same diameter as the bullet. Fire many rounds of ever a 22 LR lead bullet, this will wear away the lands/rifling. Harder alloy/metal = more wear.
     
    Last edited: Jun 26, 2012
  7. Hacker15E

    Hacker15E Member

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    Here's a pic of the "sandwich" that makes up the bi-metal jacket on Wolf .223.

    [​IMG]
     
  8. JohnBT

    JohnBT Member

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    "Technically copper/lead bullets are bi metal."

    Bimetal refers to two layers of jacket material (like copper covered iron), and not to the core whatever it is. I think we need to define terms here. Two metals mixed in an alloy wouldn't be bimetal either.

    The Wolf .223 appears to be jacketed with tombac - an alloy.

    "Tombac is an alloy formed from copper (84 - 90%) and zinc (10 - 16%) - The addition of arsenic produces White Tombac. "
     
  9. 243winxb

    243winxb Member

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    Good point. What is Bi-Metal. :uhoh: I see some Wolf bullets are steel, with .005" copper coating.
     
    Last edited: Jun 27, 2012
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