This is why firearms are never ported on the bottom of the barrel, as that would exacerbate muzzle rise, rather than mitigate it.
The goal of this investigation was to reduce the noise load from shots with large guns in the vicinity of military testing facilities and other facilities where shooting is done from defined positions … The general idea of this type of muffler is to expand the propellant gases into an appropriate tank and store the gas there until pressure and motion are low enough that they can leave the tank in a steady subsonic flow into the surrounding air.
Individual states and several municipalities also have their specific requirements.
In other countries, their possession or use is more restricted.
With the use of subsonic ammunition, the resultant sound waves effectively cancel out one another, and with the exception of the sound of the action cycling, completely eliminate any gunshot sound.
Gun control advocates have said that changing the name from "silencer" to "suppressor" is semantic propaganda similar to the efforts to avoid terms like "" or "" in favor of friendlier-sounding language like "", while gun-rights advocates make essentially the opposite argument, and also that the widespread term silencer reflects technical ignorance and is poorly defined.
Many manufacturers will not warranty their rifle suppressors for wet fire, as some feel this may even result in a dangerous over-pressurization of the silencer.
More About Vent Silencers A vent silencer is a device that is intended to reduce the noise levels created when high-pressure gas or steam is expanded to the atmosphere.