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762x39 154-grain soft-point _VS_ .308 fmj 150grain

Discussion in 'Rifle Country' started by jlott00, Jan 5, 2010.

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  1. jlott00

    jlott00 Member

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    another noob question

    will a 154 grain 762x39 have the same power as a .308 150 grain?
     
  2. rizbunk77

    rizbunk77 Member

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    I don't think it would even be close. Especially if one is allowed to compare handloads.
     
  3. hogshead

    hogshead Member

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    39 vs 51 dont think so
     
  4. Maverick223

    Maverick223 Member

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    In a word...No!

    The sissy little 7.62x39 154gr. has a velocity of about 2100fps, thus giving it about 1500ft/lbs of energy.

    OTOH the mediocre 7.62x51 (or rather the .308Win.) 150gr. has a velocity of about 2900fps, thus giving it about 2700ft/lbs of energy.

    ...And the much manlier .300WM 150gr. has a velocity of up to 3300fps, thus providing a generous 3600ft/lbs of energy.

    So in short...they lied...size does matter. :D
     
  5. memphisjim

    memphisjim Member

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    ok i think you asked your question wrong
    im assuming you mean stopping power of the 7.62x39mm vs a fmj in a 308
    id say that within 300 yards the softpoint bullet will do more damage to a flesh target
     
  6. Maverick223

    Maverick223 Member

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    In that case I agree, the FMJ will have more "power" (or energy), but less energy deposited into the target (will punch a clean hole, and energy spent going through a neighboring tree doesn't count), and a smaller diameter hole (barring tumbling, fragmentation, et cetera), creating a smaller permanent cavity and perhaps a smaller temporary cavity as well...and have LESS "stopping power" than the soft point with less energy...UNLESS you are trying to stop a Buick. :D
     
  7. jlott00

    jlott00 Member

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    well ill admit...i dont understand "grain" size's.....

    i thought a 154 grain x39 would have the same power as a 150 grain x51 in a smaller bullet.....again im a noob..sorry
     
  8. hogshead

    hogshead Member

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    They both shoot the same diameter bullet . The 308 has more case capacity meaning it pushes the same size bullet faster.
     
  9. elmerfudd

    elmerfudd Member

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    The 154 or 150 refers to the bullet weight. In this case they're just about the same. The x39 and x51 refer to the length of the brass case. That means the x51 has considerably more powder driving that bullet. More powder means more velocity, which means more energy and the capability to penetrate further or do more damage.
     
  10. jlott00

    jlott00 Member

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    oh ok, makes since now...thanks
     
  11. NG VI

    NG VI Member

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    7.62x39mm is the caliber/one of the case dimensions (length), .308 is basically identical to 7.62x51mm, it has much more horsepower than any 7.62x39, regardless of bullet weight, which is the grain number you are seeing and asking about. A .308 with a lighter bullet, like Hornady's 110, or one of the 125s, will have more power than a 154 7.62x39mm.


    The 7.62x39mm is an intermediate cartridge designed for lighter, smaller rifles, while the .308/7.62x51mm is a full-power rifle round.
     
  12. W L Johnson

    W L Johnson Member

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    This may help
    7.62x51 is the 1st one 7.62x39 is the 2nd
    Notice the longer case, 51mm vs 39mm
    [​IMG]
     
  13. Maverick223

    Maverick223 Member

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    WL, what are the third and fourth cartridges? .260Rem (with a gigantic, short ogive bullet) and 6.5Grendel?

    Grain is a unit of measurement for weight, there are 7000 per pound. The measurement is used for both the measurement of the projectile and the weight of the powder charge. In this case the bullet weight is nearly identical, the powder charge is very different (more than double the powder in the .308Win.). The grain weight that is generally listed on a box of cartridges indicates the bullet weight. The formula for kinetic energy is KE=0.5MV², where M=mass and V=velocity.

    :)
     
    Last edited: Jan 6, 2010
  14. Shadow Man

    Shadow Man Member

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    Thank you Professor :D

    While this seems to be a dying horse, I'll throw my hat into the ring anyway. Unequivocally, a 154gr SP in x39 will not have the same "power" as a 150gr FMJ in x51. In a soft target, the SP will have a more massive and immediate energy dump than a FMJ, but that in no way translates into more "power".

    And is it just me, or does 154gr's seem a tad heavy for a x39? I don't think I've ever seen commercial loads over 130grs...but I don't look around much, just get what I need and get out.
     
  15. Maverick223

    Maverick223 Member

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    Anytime pupil. :D

    It is a somewhat common load, and is available in commercial offerings.

    :)
     
  16. scythefwd

    scythefwd Member

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    Shadowman, the x39 is slightly more powerful than the .30-30. Depending on the manufacturer of the x39, it will have a .308, .310, or possibly a .311 diameter projectile. As to bullet weight, the .30-30 handles much heavier projectiles than 150gr, so I would expect the x39 to be able to do so (subject to over pressurization and OAL of the finished cartridge). The largest load data I have for the x39 is a 150 gr, but those loads are 9k psi under max pressure from what I can tell.
     
  17. NG VI

    NG VI Member

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    I thought the x39 was slightly less powerful than the 30-30, on account of similiar average velocities but heavier average bullets?
     
  18. Maverick223

    Maverick223 Member

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    Here is a link for some relatively common 154gr. cartridges (along with a few others): Wolf 154gr. 7.62x39mm

    It does, even with a 150gr. it is superior by a decent margin. It throws a 150gr. projectile about 2400fps, for about 1900ft/lbs of energy. Only at much longer ranges does the spitzer of the x39 begin to catch up due to the more favorable BC.

    :)
     
  19. Shadow Man

    Shadow Man Member

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    I'm not worthy, Master :bows: :D

    My .30-30's are all 180grs, and my x39's are all 123/124grs. Now, my ballistic understanding is not on par with others here, but with just a cursory glance at the two rounds, I would think that loading a 180gr bullet in a x39 would drop the energy output considerably, reducing the range/penetration, thinking of the OAL of the two cartridges. So at the same time, would greater energy/penetration/range be achieved with the .30-30 by handloading 100gr bullets? (I have some 100gr bullets around here, so it's not a totally hypothetical question)
     
  20. Al Thompson

    Al Thompson Moderator Emeritus

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    Energy, yes, penetration - it depends on the bullet construction. Obviously a FMJ 100 grain bullet would out penetrate a JHP, all other factors being equal.

    A popular load around here (small deer) is a 125 gr. JSP in a .30-30. I tend to favor the factory standard 170 loads in .30-30 - bit better penetration.
     
  21. Shadow Man

    Shadow Man Member

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    Thank you sir. I'm not entirely sure what the construction is; I believe semi-jacketed SP, but I could be mistaken. I'd have to go dig the boxes up.
     
  22. Dr. Tad Hussein Winslow

    Dr. Tad Hussein Winslow member

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    If I was wanting to put something down inside 100-150 yards, I'd take the x39 154 SP. You can get off a second shot from a semi in the time it takes you to recover from .308 recoil, and the expanding bullet is gonna be more effective even at slower velocity, or about the same.
     
  23. Boba Fett

    Boba Fett Member

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    http://www.65grendel.com/faq.htm

     
  24. Snowdog

    Snowdog Member

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    Whoo hoo, I got all of them right. (The 6.5x55 was hinted to by the longer case length and military-esque cupro nickel jacketed bullet, that and I one an M96).
     
  25. Maverick223

    Maverick223 Member

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    Should have known that...the rim and slightly longer OAL is a dead give away.

    :)
     
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