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Seating depth-precision delta

Discussion in 'Handloading and Reloading' started by Daniel1120, Dec 4, 2008.

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  1. Daniel1120

    Daniel1120 Member

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    Got some 9mm 124 gr rn from them, but don't know what depth to seat them at, can't find anything on their site either. Any help?
     
  2. Chief-7700

    Chief-7700 Member

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    What do your reloading books state for COL?
    Chief
     
  3. Daniel1120

    Daniel1120 Member

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    Lee says 1.150, and speer says 1.135.
    That is using the 125 gr jacketed from the lee book, it doesn't list unique with 124 grn.
     
  4. rfwobbly

    rfwobbly Member

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    Daniel -
    If you'll study the manuals closely you'll probably see that for the same type of powder, the cartridge with the shorter COL also calls for less powder.

    For a given bullet, a shorter cartridge means the bullet is seated deeper in the case. The deeper the bullet is seated, the smaller the volume remaining inside the case. A smaller volume requires less powder to burn to achieve the same chamber pressure. Follow?

    The volume inside a 9mm case is tiny as compared to something like a 38 Spl. So on a 9mm, small volume changes means big swings in chamber pressures.
     
  5. Daniel1120

    Daniel1120 Member

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    You are exactly right. I was wondering why lee's min and max charge was a well below speers. Makes perfect sense now.

    Now should I seat the bullet to lee's depth or speers? If im using the same components everytime I would rather not have two seating depths.
     
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