8X57 bullet diameter tolerance question

Discussion in 'The Ammo & Reloading Forum' started by pundip, Nov 29, 2011.

  1. pundip

    pundip New Member

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    I have purchased a sporterised Mauser 98 which I have yet to fire. I intend to reload for it and have gotten most of what I need and was measuring bullet diameters. I have some military surplus ammo which I measured after the crimp and the bullet diameter was well within or below .323. Most were between .321-.323. The bullets that I bought (Hornady Interlock 170 grain) measured on average a little over say .324 some a little more. These bullets are marked .323. With this create any pressure problems? I am very interested in not having anything blow up in my face. Is there any upper limit beyond which a bullet should not be used?
  2. Bindernut

    Bindernut Well-Known Member

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    Are you positive of the accuracy of your caliper down to 0.001"
    The Hornady 8mms that I've got on my shelf measure right at 0.323" (possibly up to 0.3235" or so...that's measuring with a Mitutoyo caliper that gets checked monthly. My micrometer is at work so I can't measure any tighter tolerance than that right now.)

    Even if they do measure .324" you're fine if you've got a newer '98. Unless...
    The big concern that people usually hear about 8mmx57 ammo is the old J ammo which used a .318" bullet instead of the modern .323" that debuted with the JS loading in 1905.
    You have to be very careful with those older Mausers (mainly '88s but also some early '98s). Also commercial Mauser sporters can be found with the old J bore all the way up into the post-WWII period, but all Military Mausers after 1905 will be the larger JS bore size.

    But as with any handloading project, start with the minimum loads and work your way up watching for pressure signs as you increase the charge. If you're using the Hornady manual for data, their 8x57 data is on the conservative side too for the rifle they used so that's an extra bit of safety margin as well.
  3. Bindernut

    Bindernut Well-Known Member

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    I should also add that the Winchester bulk 8mms that I've got on the shelf DO measure .324". I've had no problems with them pressure wise compared to the Hornady or Speer 8mms that I've used in my 8x57s.
  4. pundip

    pundip New Member

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    Bindernut the calipers I have to say are not state of the art. They are of the cheap digital variety. The milsurp on average is measuring less than the Hornady sample size of 10 or so. I realize the difference is small but being totally new to this I was not sure if it mattered and if I could trust what the box said. I don’t think it’s the older .318 bore but I am not really sure how to check it.
  5. Bindernut

    Bindernut Well-Known Member

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    Your bullets are fine even if they do measure in at .324". Plus or minus 0.001" usually won't cause any problems unless you're running a smoking hot maximum load.
    You will find some lot to lot variation sometimes from all of the bullet makers...diameter might change a bit and weight can vary a few grains.

    And a belated welcome to TFF. Lots of great guys around here to answer any other questions you might have too.
  6. JLA

    JLA Well-Known Member

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    pundip.. You will have to slug your bore to determine the diameter. 90% of 8mm mausers are .323 JS bore but every once in a while you will get an old .318 J bore. Commercial 8mm mauser ammo is loaded down to account for the older bores because someone somewhere will shoot .323 ammo in a .318 bore, and they download it to ensure itll shoot safely.
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