bearing surface & pressure

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by winmagman, Jul 10, 2004.

  1. winmagman

    winmagman Well-Known Member

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    I'm in the process of finishing the stock for a new 6.5-.284 win.. So it's time to start reloading for it.
    I've been going through my manuals and am a little confused.
    Nosler lists 52.5 grs of Re 22 or 50.0grs. of IMR 4831 for their max load with a 140 gr partition.
    Sierra lists 47.5grs of Re22 or 46.7grs of IMR 4831 for their max load with a 140 gr Matchking.
    Now I realize a bullet with a longer bearing surface will have little a higher pressure, but my question is how much does a bullets bearing surface affect pressure. Does Sierra just err on the side of caution or is there a justification for a nearly 5 grain max load difference with a 140 gr bullet?
    Thanks in advance
    Chris
     
  2. dbhostler

    dbhostler Well-Known Member

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    I may be wrong, but I think every loading situation is different, bbls., brass, primers, chamber etc., and I think they are up front with their data. I have found some max loads in at least one of my rifles is below max in someone elses with the same barrel, twist and bullet. Guess you'll have to work with data as a guide and find max for your weapon. Good luck, [​IMG]
    db
     
  3. Dave King

    Dave King Well-Known Member

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    What's the publish dates on the loading manuals? I have some older loading books and they tend to have "hotter" loads listed.
     
  4. winmagman

    winmagman Well-Known Member

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    Dave
    The Sierra is a year old and the Nosler is the fifth edition printed in 2002.
     
  5. MAX

    MAX Well-Known Member

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    I agree with db, the variables are many and in some cases complex. Comparing the Partition with the MK is apples and oranges. One has exposed lead on a flat base, the other a copper healed boat tail. Bearing length aside, you will get different levels of obturation, different barrels/actions/components were used to develope the loads and to "argue" the data is akin to arguing with a stop sign.

    On another level however, I've always viewed load manuals as guidelines, not the gospel.

    *I was known as MAX until I had a name change operation.

    [ 07-12-2004: Message edited by: DigitalDan ]