Supersonic ammunition is the name for ammunition that is designed so that its projectiles leave the barrel of a firearm with a muzzle velocity above the speed of sound . If the ammunition is designed for a lower muzzle velocity, it is subsonic ammunition .
When they are shot, there is a loud projectile bang in addition to the muzzle bang . A sound wave emanates from the air at the tip of the projectile, which is compressed into a shock wave . This wave front is shaped approximately like a rotational hyperboloid and follows the slowing down projectile. A second, roughly conical shock wave with a slightly smaller apex angle occurs at the rear of the projectile (or a little behind it). Weaker vortices emanate from the edges of the projectile in particular . So-called Prandtl expansion zones are formed at flatter floor transitions.
- Peter G. Kokalis, NR Parker, Alan Paulson, "Silencer History and Performance: Cqb, Assault Rifle, and Sniper Technology", Paladin Press (May 2002), ISBN 1-58160-323-1