CMJ vs FMJ

Discussion in 'Reloading' started by CaptainXL, Nov 1, 2012.


  1. CaptainXL

    CaptainXL
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    I have someone that wants to sell some MG CMJ 124 Gr 9mm pretty cheap.

    I have never loaded any CMJ but assume that I can use my favorite 124 Gr FMJ load safely. Am I correct in assuming that I would reload just the same as if they were FMJ?

    What is the difference between CMJ and FMJ? I think that I read somewhere a while back that the base is different. Is the base fully encapsulated?

    What, if any, are the advantages of CMJ compared to FMJ?
     

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  2. Boxerglocker

    Boxerglocker
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    Jacks #1 Fan

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    CMJ just as you stated fully encapsulated, FMJ has an exposed lead base.

    Advantage of CMJ loads is less smoke and chance of lead exposure.
     

  3. SARDG

    SARDG
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    Right now I am using MG bullets exclusively; among them 147 CMJ and 230 CMJ. I have had great performance as for as accuracy, and (with my VV powder), no smoke. I've popped a few of the 230s out of the sandy berm and I think I can buff them out and re-use them. (Just kidding... but except for some minor serrations, they look pretty good.)
     
  4. Colorado4Wheel

    Colorado4Wheel
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    CMJ don't lead the compensator like FMJ can.
     
  5. shotgunred

    shotgunred
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    reloading nut

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    The indoor range I go to in the winter requires CMJ's.
     
  6. CaptainXL

    CaptainXL
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    No one has answered my question regarding reloading CMJ.

    Are they loaded the same as FMJ?

    Should/can I use my favorite FMJ loading in CMJ?

    I assume so but want to make sure.
     
  7. F106 Fan

    F106 Fan
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    Like everything else in reloading, the answer is probably 'maybe'.

    I don't load anywhere near max so I would just use the same recipe. If I were truly concerned, I would back the load off a couple of tenths of a grain and work back up.

    I have used some CMJ in 9mm and I don't recall doing anything special.

    Richard
     
  8. Hoser

    Hoser
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    Same same.

    You are good to go.

    I load 230 and 115 CMJs with the same powder charge as normal. No difference.
     
  9. CaptainXL

    CaptainXL
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    I don't load near max either and therefore will use my normal favorite load and watch for any abnormal signs.

    Thanks for the input.
     
  10. Colorado4Wheel

    Colorado4Wheel
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    Like Hoser, we have tested the difference between CMJ and FMJ in 9mm. They work the same.
     

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