Bullet bow shockwave
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The bullet bow shockwave is the result of air being greatly compressed at the front-most tip of the bullet as it slices through the air. As the bullet moves forward a broadening wave of compressed air trails out diagonally from the bullet tip. The sides of the bullet create a conical waveform. This conical waveform may be audible to a witness as a whip-crack sound.
A bullet bow shockwave will be heard by any witness as long as the bullet speed is faster than the speed of sound, whether the bullet was fired from a weapon giving off an openly audible muzzle blast, or a mechanically-suppress-fired muzzle (Suppressed weapon) blast. If a bullet is fired from a suppressed weapon, a witness can mistake the bullet bow audible shockwave whip-crack for the weapon muzzle blast audible wave, which is a separate audible event. It might be noted here that if one is involved in such an event, that the sound you hear from a suppressed weapon will not be from the point of origin. Most humans will perceive the sound as being omnidirectional or as emanating from the bullet as it passes by.