Unexpected Primer Sign. . . not pressure

Discussion in 'Handloading and Reloading' started by edwardware, Sep 30, 2019.

  1. edwardware

    edwardware Member

    Feb 23, 2010
    I had never seen this before, and thought it might be interesting:

    So there I am, at the range, firing a carefully worked up experiment over the chrony. .223 Remington, <0.002 headspace, S&B SRP, 69gr BTHP, H4895, 1.2 grains below this rifle's pressure sign threshold. . . and this pops out of the chamber:
    What in the world? Chrony says velocity is right on target with the rest of the batch, all the other primers are healthy, and the primer appears to be collapsed IN, not out. Two more occur in the rest of the batch, and now I'm really wondering.

    A few minutes at home with a decapping die and loupe. . . and I solved it. The primers look like this:
    Notice that the bulge around the rim shouldn't be possible, because the pocket should be in the way; also note that the primer skirt appears shorter than it should be, exposing the anvil feet.

    And here's why:
    This batch of brass was swaged (on a Dillon, not by me), and apparently at least three of the batch were slightly overswaged, pushing what should be the entry radius down into the pocket. The firing pressure expanded the primer rim out into that void and pulled the primer skirt up in the process.

    Here's a property swaged example to compare:

    There were no apparent ill effects, but this is a failure mode I have never seen before.
    Last edited: Sep 30, 2019
  2. 460Shooter

    460Shooter Member

    Feb 12, 2011
    That's interesting. I haven't started loading any rifle cartridges yet. Will make a mental note.
  3. Hooda Thunkit

    Hooda Thunkit Member

    Jul 10, 2017
    Oklahoma, out in the red dirt.
    I must admit, after 30 years of reloading that's the first time I have ever seen that.

    Good job chasing it down. One gets a certain satisfaction doing that.
    Demi-human likes this.
  4. jmorris

    jmorris Member

    Sep 30, 2005
    That looks more like a super D duper swage ;)
  5. mdi

    mdi Member

    Dec 31, 2007
    As a lifelong machinist/mechanic, I had always thought this was possible with reaming and swaging primer pockets. Especially when a reloader is on a roll and "mass produces" swaged primer pockets I just thought it possible to get some a little crooked and either oval the pocket or alter the angle of the pocket. No, it doesn't happen often and I'm sure milions of cases are swaged correctly, it's just my experienced thinking...
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