Man, boredom in the boardroom, necromancing again. Delete if you like Clint.
So, anything that breaks the sound barrier make a boom, or crack. The size of the object determines the intensity of the noise. For example, the tip of a Pidgin, or Dove wing make a distinct snapping sound when vigorously flapped, because the wing tips exceed the speed of sound. When you snap a wet towel, the tip is also exceeding the speed of sound. It is also why, in a Pennsylvania or Kentucky long rifle there is a distinct crack, as opposed to a musket that just goes boom, it is the ball leaving the muzzle at supersonic speeds.
Any suppressor cannot silence this issue, it will silence the muzzle blast, but if the round is moving FTS, it will still Crack, which is why the favorite weapon for up close Assassinations for years was a Suppressed .22 short hammerless revolver, wrapped in a towel, the revolver was used because there was no slide action, it is amazing how noisy a slide can be once the muzzle blast is suppressed, and the round is travelling subsonic.
Anyway, there is that, also the .458 SOCOM was specifically designed for suppressed applications, it is subsonic, and as such, very quiet, while delivering a large amount of energy. Great for dealing with nuisance hogs, because they will not scatter due to the noise.
As far as energy, Kinetic Energy = Half Mass X Velocity Squared, this is how and A1 Abrams can defeat Russian tanks with reactive armor, with either a Depleted Uranium, or Tungsten penetrator, with no explosive, just a sharpened rod with fins.
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