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Fire Forming ? ...

Discussion in 'Black Rifle Forum' started by deputy tom, Feb 22, 2012.


  1. deputy tom

    deputy tom
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    While shooting .223 out of a 5.56 chamber are we fire forming the brass? I was wondering if reloaders should seperate the two different types of brass. TIA. tom.:dunno:
     

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  2. farmer2

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    Yes you are, but it doesn't make up for the major difference which is the case volume. 556 brass is thicker allowing for less powder. Thus leading to higher pressure. If you handle .223 brass and 556 you can actually feel the difference.

    farmer2
     

  3. MajorD

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    after shooting in a semi auto you need to full length resize anyway so any fire forming is reduced back to standard average dimensions anyway. I prefer to use a small base sizer which is even tighter- more likely to get the brass resized to fit in a larger variety of rifles especailly when we talk about match chambers. also carefully checking length and trimming or discarding over length cases will minimize problems as well.There is no external dimension difference between 223 and 5.56 as a general rule
     
  4. deputy tom

    deputy tom
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    Thank you for the replies. I now have my answers.tom.
     
  5. DirectDrive

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    This. ^^^

    The .223 chamber has a shorter freebore than 5.56 and this is why it is not a good idea to run higher pressure 5.56 in a .223 chamber.
    The .223 chamber can run those already higher pressures up even higher with the shorter freebore.

    Fireforming generally refers to making a significant change in the geometry of a case using the fireforming method.
    The Ackley Improved calibers are an excellent example of fireforming.
     
  6. Magelk

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    There's no way you're going to feel the difference.:rofl:
     
  7. farmer2

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    I absolutely can feel the difference between 223 brass and 556. Grab some LC labeled brass and some winchester .223 brass and you will be able to as well. I can pick 223 brass out of pile of 556 quite easily without looking at the rollmark.


    farmer2
     
  8. QNman

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    I just measured a Winchester .223 brass (shiny new) and a WCC 07 casing with a caliper and on the powder scale. ALL exterior dimensions are identical and both weigh precisely 6.05gr. Any difference in case is unlikely to be perceived by mortal hands.

    Also, if both cases are identical in their exterior dimensions, then no significant fire forming is occurring. I believe all cases suffer some degree of fire forming, which is why we resize the cases before loading. However, it does not appear there is a significant external dimension difference to say that we are fire forming .223 to a 5.56 case.

    IIRC, the case at the head has a different profile from 5.56 to .223 to accommodate the greater pressures of 5.56 ammo. I believe that is on this site somewhere, but will have to look when on a "real" computer.
     
    #8 QNman, Feb 25, 2012
    Last edited: Feb 25, 2012
  9. Magelk

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    Like QNman said, "Any difference in case is unlikely to be perceived by mortal hands."


    I've weighed thousands of cases in my time and the difference is so slight, you will never be able to tell the difference.
     
  10. QNman

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    My scale says they both weigh 6.05 grains.
     
  11. farmer2

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    are you sure that scale is working properly?



    farmer2
     
  12. Magelk

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    OK, couldn't resist. I just went and weighed about 6 different kinds of cases (with spent primers, all cci41's) The Lake City cases were lighter by a grain or so than Winchester cases, PSD's, PMC's, and FC (american eagle). They were about the same as the WCC's.
     
  13. QNman

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    :rofl:

    Yes... I keep it calibrated regularly to prevent breech fires. You sure your fingers are working properly? Try it blindfolded. I betcha there is a slight visual cue you are picking up subliminally.
     
  14. QNman

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    I weighed mine clean with no primers. And only compared Winchester .223 to WCC 5.56
     
  15. Magelk

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    I think he was asking if your scale was working properly because 6.05 grains is close to 90 grains short!

    Mine, with spent primer were coming in at 96 grains.
     
  16. QNman

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    Oops... I mean GRAMS. :embarassed:
     
  17. Magelk

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    LOL, thats actually what I thought you had wrote but reread and saw grains!
     
  18. QNman

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    TOTAL brain fart!
     
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