Simple Q: Is .40 S&W sub- or super-sonic?

Simple Q: Is .40 S&W sub- or super-sonic?

This is a discussion on Simple Q: Is .40 S&W sub- or super-sonic? within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; I am asking about various .40 factory ammunition. Examples: Speer Lawman Federal Hydra-Shok Winchester (target ammunition) Are these (or others) in .40 typically a SUB- ...

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Thread: Simple Q: Is .40 S&W sub- or super-sonic?

  1. #1
    VIP Member Array peacefuljeffrey's Avatar
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    Simple Q: Is .40 S&W sub- or super-sonic?

    I am asking about various .40 factory ammunition.

    Examples:
    Speer Lawman
    Federal Hydra-Shok
    Winchester (target ammunition)

    Are these (or others) in .40 typically a SUB- or SUPER-sonic handgun round? I just don't know, and I'm curious. Thanks.

    (Please state velocities if known, as well as what the FPS conversion of the speed of sound is. Thank you.)


  2. #2
    VIP Member Array Bud White's Avatar
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    should be supersonic or close as you can buy subsonic 45 ammo

    According to a google search speed of sound at sea level = 1116.43701 feet per second

  3. #3
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    Speed of sound is nominal 1100fps.

    Checking just for now on reload data as a guide. Most 180 grainers seem to be well below that, some even below 1000 fps. 165 grainers all seem sub sonic but only just in some loadings.

    155 grainers do exceed super sonic but don't know of any factory loads with that light of a bullet offhand.

    No factory figures right now but this might give some idea for starters.
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  4. #4
    VIP Member Array Bud White's Avatar
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    Sound travels through air at "the speed of sound." Officially, the speed of sound is 331.3 meters per second (1,087 feet per second) in dry air at 0 degrees Celsius (32 degrees Fahrenheit). At a temperature like 28 degrees C (82 degrees F), the speed is 346 meters per second.

    As you can see, the speed of sound changes depending on the temperature and the humidity; but if you want a round number, then something like 350 meters per second and 1,200 feet per second are reasonable numbers to use. So sound travels 1 kilometer in roughly 3 seconds and 1 mile in roughly 5 seconds.


    Another version but the fps is close

  5. #5
    VIP Member Array Bud White's Avatar
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    155 winchester silver tip

    Velocity (fps) Energy (ft.lbs.) Mid-Range Trajectory (in.)
    Muzzle 1205 500 -
    50 1096 414 0.8
    100 1018 357 3.6

    165
    Muzzle 1130 468

    So looks like most break it at the muzzle

  6. #6
    VIP Member Array peacefuljeffrey's Avatar
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    Thank you for the replies. I did go to Wikipedia and found a table of speed of sound. I had a fun time converting the 661 knots back to fps. (Since I fly, I like knots.)

    What I did not know was if the typical store-bought rounds are likely to be sub- or super-sonic.

    Thanks for the answers.

  7. #7
    Distinguished Member Array AutoFan's Avatar
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    Looks like the 135 and 155 grain bullets are supersonic at the muzzle, the 165 grain can be either and the 180 grain are subsonic (all of these are from the manufacturers numbers and the speed of sound at STP [Standard Temperature and Pressure]).
    Last edited by AutoFan; March 15th, 2007 at 12:22 AM. Reason: spelling

  8. #8
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    Quote Originally Posted by P95Carry View Post
    Speed of sound is nominal 1100fps.

    Checking just for now on reload data as a guide. Most 180 grainers seem to be well below that, some even below 1000 fps. 165 grainers all seem sub sonic but only just in some loadings.

    155 grainers do exceed super sonic but don't know of any factory loads with that light of a bullet offhand.

    No factory figures right now but this might give some idea for starters.
    Factory loads go as low as 135 grain

  9. #9
    Distinguished Member Array Chooie's Avatar
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    Hornady TAP 155gr looks to be supersonic as well.


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