30-06 vs. 30-378

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by hemiford, Mar 5, 2014.

  1. hemiford

    hemiford Well-Known Member

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    Oct 7, 2013
    In this post I am touching on several BIG topics, but I'll try to sum them
    up with one question.

    22" barrel length is common to many 30-06 rifles. Since a 30-378 Wby
    has very close to twice the powder capacity, why doesn't a 30-378 rifle
    have a 44" barrel ?? This would give each rifle the same expansion ratio.

    ???

    On a side note, this should also give the 30-378 bullet about 1.414 times
    the muzzle velocity of the 30-06 (same bullet weight).
    I.E., 3800 fps vs. 2700 fps.

    I have done a lot searching to find graphs of the internal pressure traces
    of large capacity cartridges, to compare with a typical 30-06 pressure trace,
    and have not found good comparative results.

    I have done this with gasoline engines and compression ratio, which is a
    VERY similar situation.

    Aside from the inconvenience of carrying around a very long barrel, I see
    this as a simple engineering exercise in scaling.
     
  2. MudRunner2005

    MudRunner2005 Well-Known Member

    Messages:
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    Oct 13, 2008
    Wow...That scared me when I saw the title. I thought you were wanting to compare the 2 ballistically. :D

    I was gonna say, that's about like comparing a slingshot to a tomahawk missle. LOL

    The .300 Sherman is a better ballistic comparison than the standard .30-06. But they're still far apart.

    Also, the .30-06's really will shine with a 26" barrel.

    The reason they don't need a 22" vs 44" barrel is because even though it has twice the powder, the powder won't burn as fast creating more pressure to push the bullet faster, therefore it doesn't need a 44" barrel. The .30-06 will use a faster burnng powder only requiring a 22-24" barrel to reach good velocities.
     

  3. LONGSHOOTER

    LONGSHOOTER Well-Known Member

    Messages:
    178
    Joined:
    Oct 21, 2007
    You talk as if these processes are to occur in a linear fashion.

    My suggestion? Keep studying.
     
  4. Michael Courtney

    Michael Courtney Silver Member

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    Nov 15, 2010
    If you're going to get the same efficiency with the same bullet weight, you'd need a much longer barrel.

    Overbore cartridges are much less efficient, but it helps that most overbore cartridges are used with longer, heavier, high BC bullets. A 208-230 grain bullet can use the extra powder in a shorter barrel length than a 150-165 grain bullet.

    But adding more powder capacity and much greater powder charges to a cartridge is almost always a situation of demishing returns.