 Suppressors help to reduce the muzzle report of firearms by providing a larger area for the propellant gas to expand, decelerate and cool before release sound energy into the surrounding.The overpressure wave from a firearm's muzzle blast can contain a significant amount of energy because it travels at an extremely high velocity.Residual pressures at the muzzle can be a significant fraction of the peak bore pressure, especially when short barrels are used.