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Thread: Pressure Curve for 230 gr 45 ACP

  1. #1
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    Pressure Curve for 230 gr 45 ACP

    Is there a pressure curve available somewhere for a typical 45 ACP load, e.g. 5" barrel, 230 gr bullet, 850 fps?

    QuickLoad used to have a demo program available that could generate one, but it's no longer available.
    And of all the curves floating around the interwebs, none that I can find are for the 45 ACP.

    Also, is there a typical relation between peak pressure and the lower pressure at bullet exit? For example, if peak pressure was 18,000 psi, what might the pressure at bullet exit be?

    This is all for an article, not for reloading purposes.

    -

  2. #2
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    Too much depends on how fast the powder burns. Depending on burn speed, the pressure may peak before the bullet leaves the barrel, but a slower powder might require a longer barrel to achieve peak pressure.

    I don't think you'll get a pressure curve, but you may get a better idea what I'm talking about if you go to the Ballistics by the Inch web site. I'm certain they've done .45 ACP. They start with a long barrel, measure muzzle velocity, then chop an inch off the barrel and measure again. Their data are fairly complete, and very interesting.
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside
    Last edited by Hawkmoon; 8th April 2018 at 22:49.


  3. #3
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    Quote Originally Posted by Hawkmoon View Post
    Too much depends on how fast the powder burns. Depending on burn speed, the pressure may peak before the bullet leaves the barrel, but a slower powder might require a longer barrel to achieve peak pressure.

    I don't think you'll get a pressure curve, but you may get a better idea what I'm talking about if you go to the Ballistics by the Inch web site. I'm certain they've done .45 ACP. They start with a long barrel, measure muzzle velocity, then chop an inch off the barrel and measure again. Their data are fairly complete, and very interesting.
    Thanks, I'll take a look.

    For a 5" 1911 though, wouldn't there be some powder burn rate that was settled upon by now?

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  4. #4
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    Look in any reloading manual under .45 ACP. You'll find loads for a number of different powders. Each has a different burn rate. No, there is no "settled" burn rate for the 5" 1911 in .45 ACP.
    Hawkmoon
    On a good day, can hit the broad side of a barn ... from the inside

  5. #5
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    Many of the common powders for .45 ACP will have reached peak pressure before the base of the bullet even clears the case.

  6. #6
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    May have found one.

    Does this look typical?

    Bullet weight is 230 gr
    Muzzle velocity is about 850 fps
    Peak pressure is about 17,000 psi
    Muzzle pressure (at bullet exit) is about 3000 psi

    Pressure_Curve_1.jpg

  7. #7
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    Good find! Where did you find it?
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  8. #8
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    How long is that bullet?

    Peak has come and gone before is cleared the case.

  9. #9
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    Here's an analysis of all this stuff: http://yarchive.net/gun/pistol/1911_dynamics.html
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  10. #10
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    Quote Originally Posted by niemi24s View Post
    Good find! Where did you find it?
    It turned up as one of the bing images while searching for "quickload pressure curve".

    The pressure values, if typical, are exactly what I want. I would rather have a pressure vs time though for the curve shape.

    -

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