Long Range Sizing Question

Discussion in 'Reloading Forum (All Calibers)' started by JEFFPPC, Jul 12, 2018.

  1. Webster

    Webster

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    https://www.copper.org/applications/industrial/DesignGuide/performance/timestress03.html

    upload_2018-7-12_19-49-0.png

    This article was referring to electrical connectors stamped out of cartridge brass. Don't know the relationship of stress to actual hardness. I worked with many types of hardness tester instruments over the years. Hardness testers use ASTM STANDARD certified test blocks made from steel or brass depending on the hardness range. Test instruments are required to be verified with test blocks every day before use. Most test blocks are certified +/- .5 or 1.5 hardness units variation from there intended test value. The high hardness blocks have a tighter range than the softer blocks. A typical brass 80 HRB +/- 1.5 certified test block never exceeds it's stated hardness range over the life of the test block.
     
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  2. alinwa

    alinwa

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  3. Webster

    Webster

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    Are you serious? Sounds like compulsive obsessive behavior. Oxide layers are angstroms thick.
     
  4. mikecr

    mikecr

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    When you size brass you're adding energy. The brass springs back and comes to new balance, but it takes time to come to lowest energy balance. In other words, the brass continues to creep.
    This is pockets, bodies, shoulders, and necks. It appears to me that it takes ~a month to reach fully stable.

    So before an annual hunting trip I complete all case sizing and primer seating at least a month beforehand, then load just before the trip. The primers are reseated, as they creep, shoulder bumps checked & touched to 1thou as needed.
    My necks are set at 1thou under cal, and seating here expands but does not size the brass further. So this ammo is totally stable for the next couple weeks of hunting (and well beyond, some, years between use).

    This is GH hunting out to ~650yds with either 223 or 6br.
     
  5. Webster

    Webster

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    Made up metallurgy. Where do you get this lowest energy balance from? Fake News.
     
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  6. alinwa

    alinwa

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    I dunno, the way brass flows up into the (immovable) shoulders around here I sometimes think we need a viscosity index instead of the Olde Standarde's Knoop and Mohs.....donuts are changing the world.......

    And I STILL like chicken
     
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  7. mikecr

    mikecr

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    That changes occur over time is not fake news. It's observed here & there: http://bulletin.accurateshooter.com/2010/02/neck-tension-bullet-seating-and-the-time-factor/ and discussed at times.
    I'm not a metallurgist so I'll concede to better terms of energies behind it. Maybe stress,, or hoop tension.
    Keep in mind that we're not talking about a machined block of metal stock. This is dimensions and stresses we affect in a shaped metal form. If we had to size our barrels after every shot, we'd notice similar there.

    If you load ammo right before a match and shoot some remainder of it a month or two later, there is a good chance it will shoot a bit differently. If I were a competitor, I would not show up for record shooting with a mix of older and freshly loaded.
     
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  8. rwj

    rwj Silver $$ Contributor

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    Interesting! Input on this topic suggests that cartridge brass has “memory” and is trying to return to its initial state/shape. Investigation has revealed that several brass alloys were where the first efforts to develop shape memory alloys (Nitinol) started! Perhaps cartridge brass displays similar behavior?
     
  9. alinwa

    alinwa

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    Of course it does.... as anyone who's ever actually experienced it (VS those who went to school about it, or read it on the innernet) knows. I sometimes size brass so scrupulously while working up loads that if I have unfired rounds left over and let them set in the loading block, two days later THEY WON'T EVEN CHAMBER!
     
  10. pirate ammo

    pirate ammo Silver $$ Contributor

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    and I got slammed one time for saying they had MEMORY
     
  11. alinwa

    alinwa

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    not by me....

    I DO this stuff, not speculate about it.
     
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  12. pirate ammo

    pirate ammo Silver $$ Contributor

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    I know that,bad translation again
     
  13. rwj

    rwj Silver $$ Contributor

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    Shooting is a new endeavor for me and I will learn by every means possible. This includes applying previous life experiences, reading, then doing to create my own shooting experiences from which I’ll learn even more. That process is often shortened by forum members that are kind enough to share their experiences for which I’m always thankful. How it is shared is an individual decision that puts one’s character on display...
     
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  14. Dusty Stevens

    Dusty Stevens COVFEFE Gold $$ Contributor

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    Al shares a ton with us- real world experience and like he said not what he read about its what actually happens. Like i always say test it for yourself. I AM an engineer but im not typical because i know sometimes it just dont work like they say. This is an easy enough test that anybody with a set of dies and cases can do it. No elaborate setups just doing what you already do. No extra effort, no cost. Why not do it?
     

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