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Should i crimp my 9mm loads?

Discussion in 'Reloading' started by November Sunrise, Sep 23, 2010.


  1. November Sunrise

    November Sunrise
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    I have seen more than a few contradicting articles regarding the need for crimping straight wall cased ammo. Specifically the 9MM. I currently do give mine a light crimp only because i don't feel comfortable NOT doing so. My Lee dies are new and they size the case wall to a smaller diameter than the inserted bullet. The finished rounds have a bell appearance and i am sure the bullet will be held in place sufficiently by this alone but i still give em a little crimp to ensure the flare on the case mouth is gone.What are your thoughts?
     

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  2. ron59

    ron59
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    Bustin Caps

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    What you said. You're not really "crimping", but instead removing the flare. You can even measure it... at the case mouth, desired diameter is something along: .375-.377 "
     

  3. fredj338

    fredj338
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    Always, regardless of what ever article you read, always crimp psitol ammo, always. It's more rleiable & more accurate, why not?
     
  4. jdavionic

    jdavionic
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    I always crimp 9mm rounds. The last thing I was is a bullet getting pushed back in the case while I shooting a match.
     
  5. Boxerglocker

    Boxerglocker
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    Ditto.... .377 :wavey:
     
  6. njl

    njl
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    Or...bullet diameter + (brass thickness at the mouth * 2).
     
  7. lanternlad

    lanternlad
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    I remember reading an article that said crimping was better because it allowed more pressure to build up behind the bullet instead of escaping around the sides. This gives the bullet more velocity and a harder hit upon impact. I'm assuming the pressure escape of crimped vs uncrimped would be negligible, but hey, with 9mm you need all the power you can get. :)
     
  8. Zombie Steve

    Zombie Steve
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    Taper crimp to remove the flare you put on before you seated the bullet. That's all. Neck tension holds it. I think performance-wise, roll crimps for bullets with cannelures (mostly revolver rounds) can help get a more consistent ignition and leave less unburnt powder, but again, a taper crimp doesn't hold the bullet in place, neck tension does.
     
  9. fredj338

    fredj338
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    ZOmbie, right again. You get a little bit of tension out of a good TC, but it's all about neck tension.:wavey:
     
  10. 1glockfan23

    1glockfan23
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    I use the light taper crimp that the Lee seating die provides, and is usually sufficient for my 9mm and 40 rounds. I use the Lee Factory Crimp die on my revolver ammo since I load lead bullets in those.
     
  11. dudel

    dudel
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    Always crimp. Pistol rounds that headspace on the case mouth (like 9mm) get a taper crimp. Pistol rounds that headspace on the rim, get a roll crimp. Doesn't matter what kind of die you're using. Lee provided a crimp die in the set. What you percieve as neck tension means nothing.
     
  12. Colorado4Wheel

    Colorado4Wheel
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    You will use a crimp die to remove the flare but you don't actually crimp it. Look in your Lyman manual and you will see even when they talk about crimp they are not bending the case in towards the bullet. So it's symantics for 9mm. Below is drawing of what Lyman recommends with crimp. Notice it has no inward turn of the case.

    [​IMG]
     
  13. November Sunrise

    November Sunrise
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    Thanks for the info guys. Looks like the crimp die stays.
     
  14. sig2009

    sig2009
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    I try to keep at .377. If you go down to .375 with a plated bullet you are putting a deep groove into the bullet and you will be cutting into the plating.
     
  15. sig2009

    sig2009
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    I stopped using the Lee FCD because it was resizing the bullet.