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  1. #1
    RDub is offline Junior Member
    Join Date
    Mar 2011

    Underwood 10mm 180grTMJ report

    Underwood 10mm 180gr TMJ

    I found the C.O.L. to be 1.245”

    Taking a look inside I found 9.6gr of propellant that looks very much like 800-X.

    A closer look;

    The bullet weighed in at 179.4. This looks just like a Speer 180gr TMJ.

    At the range I shot two groups this time. One, with the stock spring, and the other with an ISMI 22# spring and SS guide.
    Gun is a brand new Glock 20-SF with stock (4.6") barrel.

    First, I was surprised to see such a significant velocity spread in both groups. I had velocities as low as 1155fps and as high as 1275fps. Now If I was to try to use any kind of powder measure with 800-X, I know what would happen.. Large weight variations.. So I wonder if that is happening here. I am tempted to pull down some more rounds and see what variations there might be.
    Well the ISMI spring seemed to help with accuracy a bit, and the brass stayed closer and easier to find.

    Second, this ammo is warm. Many of the fired cases produced smileys..

    The cases that did not have smileys measured;
    .4340, .4392, .4348, .4343, .4341.. These must have been the rounds that shot in the 1100’s.

    All in all, the ammo shot very well and functioned flawlessly through the Glock 20-SF. I’ll keep a magazine full of these for woods carry. I just won’t bother looking for brass..

  2. #2
    Nanuk's Avatar
    Nanuk is offline Junior Member
    Join Date
    Oct 2012
    Those certainly are hot.

  3. #3
    berettatoter's Avatar
    berettatoter is offline Senior Member
    Join Date
    Aug 2011
    The 10x25 is one bad-assed round. I don't own one, but wish I did. Nice pics.

  4. #4
    cadjak is offline Junior Member
    Join Date
    Mar 2011
    Any chance of seeing a picture of the base of the bullet Underwood used in this ammo? I shot some plain ol' green box Remington 180gr TMJ and was surprised at how thick the jacket was.

  5. #5
    papahawk's Avatar
    papahawk is offline Junior Member
    Join Date
    Jun 2012
    Aztec NM
    @ berretatoter, you are right. it ias a bad ass round I have 2 of them and going to get the Olympic Arms 10mm upper for my AR-15. My 10mm loads run in the 1400 ft/sec range with Blue dot or 800-x and a 180 gr XTP out of a Gen1 G-20 with no "smiley faces" or other pressure signs. the also run good out of my Kimber Eclipse. *note* both guns have 22# recoil springs

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