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Thread: Why are 125/130 grain .38+p so slow?

  1. #1
    Member 03RN's Avatar
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    Why are 125/130 grain .38+p so slow?

    When 158 grain bullets have no problem going 1000-1250fps?

    I'd think a 125/130 should easily be able to do the same.

  2. #2
    Quote Originally Posted by 03RN View Post
    When 158 grain bullets have no problem going 1000-1250fps?

    I'd think a 125/130 should easily be able to do the same.
    1250 is .357 mag. velocity. I clocked 900fps with 125 in a 2" 642, that's fast.

  3. #3
    Look at the relative pressures between .357 Magnum and .38 Spl (even +P) and you'll get your answer.

    Funny thing, and something I thought about starting a thread relating to this. Very similar modern revolvers are chambered in .38 SPL, 357 magnum and 9x19mm. The latter two generate the same pressure. .38 Spl is spec'ed for much less. We all know why this is (.38 Spl is such an old cartridge, there are still early guns around that can't take nearly the chamber pressures modern guns can.) But, of course by now modern guns predominate. I'm a little surprised that some "rogue" ammo maker doesn't put out a .38 super +p+ that at least approaches 9mm/.357 Magnum pressures, and explicitly declare that the ammo should only be used in guns manufactured after 1970 (to randomly pick a date.) It would have a disclaimer about the overpressure, so if it kabooms your gun, it's on you.

  4. #4
    Member 03RN's Avatar
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    Quote Originally Posted by Pistol Pete 10 View Post
    1250 is .357 mag. velocity. I clocked 900fps with 125 in a 2" 642, that's fast.
    https://www.buffalobore.com/index.ph...t_detail&p=291
    https://www.underwoodammo.com/collec...18785707491385
    https://www.defensivecarry.com/forum.../125541?page=1
    https://www.defensivecarry.com/forum.../topics/118121

    I have not chronographed my reloads but 5.2 with unique and 158gr hard cast gives me great accuracy and is much cleaner to shoot than loads under 5grains in terms of leading and carbon or unburnt powder.

    And color me surprised. Exactly what I was looking for.
    https://www.underwoodammo.com/collec...18785726955577

  5. #5
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    Quote Originally Posted by BBMW View Post
    Look at the relative pressures between .357 Magnum and .38 Spl (even +P) and you'll get your answer.

    Funny thing, and something I thought about starting a thread relating to this. Very similar modern revolvers are chambered in .38 SPL, 357 magnum and 9x19mm. The latter two generate the same pressure. .38 Spl is spec'ed for much less. We all know why this is (.38 Spl is such an old cartridge, there are still early guns around that can't take nearly the chamber pressures modern guns can.) But, of course by now modern guns predominate. I'm a little surprised that some "rogue" ammo maker doesn't put out a .38 super +p+ that at least approaches 9mm/.357 Magnum pressures, and explicitly declare that the ammo should only be used in guns manufactured after 1970 (to randomly pick a date.) It would have a disclaimer about the overpressure, so if it kabooms your gun, it's on you.
    I'm kind of surprised manufacturers don't do that with the 9mm since it's only 4 years younger than the .38 special.

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    Quote Originally Posted by 03RN View Post
    I'm kind of surprised manufacturers don't do that with the 9mm since it's only 4 years younger than the .38 special.
    Probably no need given that 9mm can achieve high velocities within its pressure spec. SAAMI max pressure for 9mm is roughly double that for .38 spl.

    ETA: Also, isn't that basically what +P+ is? No actual spec, pressures "above +P."
    Last edited by olstyn; 04-16-2019 at 06:21 AM.

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    I would LOVE to see independent pressure testing of those 38 spl +P loadings that get close to 357 mag velocities...

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    Quote Originally Posted by TiroFijo View Post
    I would LOVE to see independent pressure testing of those 38 spl +P loadings that get close to 357 mag velocities...
    I'm guessing we would run screaming into the night if we saw what some of those loads were doing pressure wise.
    Regional Government Sales Manager for Aimpoint, Inc. USA
    Co-owner Hardwired Tactical Shooting (HiTS)

  9. #9
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    Quote Originally Posted by olstyn View Post
    Probably no need given that 9mm can achieve high velocities within its pressure spec. SAAMI max pressure for 9mm is roughly double that for .38 spl.

    ETA: Also, isn't that basically what +P+ is? No actual spec, pressures "above +P."
    Was it that high in 1902?

  10. #10
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    Quote Originally Posted by Wayne Dobbs View Post
    I'm guessing we would run screaming into the night if we saw what some of those loads were doing pressure wise.
    Is there any metallurgic difference between a m10 and a m547?

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