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Full Metal Jacket?

Discussion in 'General Gun Discussions' started by 47CubPilot, Mar 13, 2015.

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  1. 47CubPilot

    47CubPilot Member

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    I've only been shooting for 41 years, so I'm a relative novice.
    I recently purchased my first 1911 style handgun (Colt 1991A1 Commander). Last Sunday I put 150 rounds of Federal Champion thru it, with absolutely no problems. :D
    I was firing into a very large pile of snow. With the warm weather in N. central IL this week the snow has really melted. Because of this, I was able to recover 102 of the bullets today.
    I always thought that a FMJ was completely enclosed, and a jacketed bullet had an exposed base.
    Well, 101 were like the one on the right, and 1 was the one on the left.
    Have I been misinformed all these years?
     

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  2. d2wing

    d2wing Member

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    As far as I know jacketed has a couple meanings, FMJ means the opening is in the base, whereas, jacketed can mean there may be a hollow point or exposed lead and the base is enclosed. FMJ is required for military bullets, soft point or hollow point is required for most hunting. It is not practical to fully enclose the core, there are exceptions but most mass produced bullets are open at one end.
     
  3. moxie

    moxie Member

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    FMJ (also called "ball") has an exposed base. The term "full" is misleading. The outer jacket starts out as a cup of copper, brass, or "gilding" metal and is "drawn" or formed over the lead core. JHP, jacketed hollow point, JSP and OTM have the jacket drawn over the lead core as well, but with the opening on the tip of the bullet.

    TMJ, "total" metal jacket, or plated, covers the whole bullet.
     
  4. jim in Anchorage

    jim in Anchorage Member

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    Any jacketed bullet must have a opening ether front or rear, as part of the manufacturing process. If it doesn't have a opening, it's plated not jacketed.
     
  5. 47CubPilot

    47CubPilot Member

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    Thanks guys. Always learning!
     
  6. Drail

    Drail Member

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    Never stop learning.
     
  7. rcmodel

    rcmodel Member in memoriam

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    As already explained a lead core is swaged into a copper cup.
    If the base of the cup is at the rear, you have a SP or HP bullet with a closed base, and an open point with lead exposed at the front.

    If the core is swaged in the jacket cup from the rear, you have a FMJ with lead exposed at the base.

    Then it gets more complicated.

    Some FMJ bullets are made with a disk covering the exposed lead in the base and crimped in place as the bullet is swaged. Sometimes called an Encapulated bullet, or FMJ EC.
    It's still a FMJ.

    Then you have Plated bullets such as the Speer Gold Dot, Berry plated bullets, and others.
    In these, the jacket is electroplated on the lead core, and has no opening, unless they swage a HP cavity in the end, as on the Speer Gold Dot HP.
    That's how they got the name.

    The Gold Dot at the bottom of the HP cavity is the remains of the FMJ plating pushed into the bottom of the HP cavity by the swaging punch that forms the HP.

    But back to the question.
    Most military FMJ bullets have the lead core exposed in the base, just as yours do.

    The one on the right is a FMJ cup & core bullet.
    The one on the left is an electroplated jacket bullet.
    (Probably the only one you found from the aluminum case Federal stuff.)

    rc
     
  8. Sheepdog1968

    Sheepdog1968 Member

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    I had heard once I think the term total metal jacket to indicate the base of the bullet was also encased in copper.
     
  9. HorseSoldier

    HorseSoldier Member

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    +1. You see "total metal jacket" sometimes. Relatively recent innovation since lead in bullets has become an environmental football in some places.
     
  10. Jim Watson

    Jim Watson Member

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    Total Metal Jacket, TMJ started out as a Speer trademark for their heavily plated bullets.
    Seems to have become generic like xerox or google.
     
  11. alexander45

    alexander45 Member

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    really hot place
    Heck I'm more intressted in the fact he was shooting into a berm of snow that's really somthing I have never really considered
     
  12. 47CubPilot

    47CubPilot Member

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    The only 45 that I have shot were the Federal aluminum case stuff.

    So far, only one that had the base covered!
     
  13. 47CubPilot

    47CubPilot Member

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    alexander45
    The snow that I was shooting into was what I had piled up. I was shooting into the long axis of a pile that was about 40 feet long, 15 feet wide and 8 feet deep. With a hill behind it, and nothing for over a mile beyond that.
    The bullets seem to have penetrated approximately 2 to 3 feet.
    They are in a neat little pile. :D
     
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