Supersonic crack with suppressor

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by silvertip44, Oct 13, 2012.

  1. silvertip44

    silvertip44 Well-Known Member

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    I am new to shooting with a suppressor on my rifles and have maybe a stupid question to ask.
    I am using the same suppressor on .223, .308 and .300 Win Mag.
    The supersonic crack is created when the bullet exceeds the speed of sound or about 1152 feet/sec. at sea level.
    My loads in the .308, for example, chrono at 2640 fps. Question is does the intensity (loudness) of the supersonic crack increase with speed or does it remain about the same. In other words, if a bullet traveling at 1200 fps cracks then does a bullet traveling at 2600 fps(a little over twice the speed of sound) produce a louder crack?
     
  2. lloydsmale

    lloydsmale Well-Known Member

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    no but it takes more powder burning to get those speeds and that will make it louder.
     

  3. brentc

    brentc Well-Known Member

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    I never noticed much of a difference in sound level between firing my 6.5 Grendel at 2300 fps and my 300 WM at 2900 fps through the same suppressor. I guess it would also depend on your suppressor design.
     
  4. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    I don't think so at least not at a level that the human ear can detect.
     
  5. Mikecr

    Mikecr Well-Known Member

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    A faster bullet would produce a denser wave, which you would perceive as being a more abrupt crack/boom -if it passed you by downrange. Same with a larger or lower BC bullet.
    But this is dragged downrange(with the bullet) from the muzzle, and all you would hear of it are reflections off the environment.
    What you'll hear shooting the gun is the pressure release, at a rate afforded by the suppressor given the amount of gas you're releasing into it and designed affect on that gas release(capacity).
    When the load exceeds suppressor capacity, then the local sound would get louder.
     
  6. silvertip44

    silvertip44 Well-Known Member

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    Thanks for the responses, I sort of suspected what I have read, but since it was 1966 when I last sat in a college physics class I couldn't quite remember.
    I am shooting with the AAC Cyclone and using it on all three of my 700s--.223, .308, and .300 WM with lower velocity loads.
    I probably won't mess with sub sonic ammo since it just wouldn't fit into any of my shooting style. I'm afraid it would be more trouble than it would be worth.
     
  7. ICANHITHIMMAN

    ICANHITHIMMAN Well-Known Member

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    physics oh man not looking forward to that class
     
  8. Kevin Thomas

    Kevin Thomas Well-Known Member

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    silvertip44,

    Absolutely, positively YES! But you're sort of asking from the wrong end, or at least that's what I get from your question. I'm still waiting for my paperwork to clear on my first suppressor, so I can't shed too much on the firer's perspective. I've used several suppresors with supersonic ammo, and they all moderated the noise at the firing point quite well. The sonic crack was still audible, but nothing too loud in most cases.

    As for that crack itself, yes, you hear a very distinct difference when the bullet goes by, depending on the speed of that bullet as it passes. Spend some time in the pits at any highpower range, and you'll understand exactly what I'm saying. When pulling the target, the shooter's bullets will pass directly over your head, usually 2-3 ft above your position. The crack produced by a bullet's passage when fired from 200 yards away is distinctly sharper than what you'll hear from that same rifle when the shooter moves back to 600 or 1,000 yards. This is not to be confused with the "Thump" of the rifle being fired, and the two sounds are each very audible, and quite different. The difference from the pits when a suppressor is involved is that you still hear the crack of the bullet passing, but not the thump of the rifle being fired.