A firearm suppressor includes a housing to be mounted to a firearm. The housing defines a lumen therein for receiving gases from the firearm. At least one stripper member is disposed in the lumen for engaging and deflecting the gases. At least one one-way flow element is disposed downstream of the at least one stripper member in gas flow direction for permitting a one-way flow of the gases. At least one decompression chamber is disposed downstream of the at least one one-way flow element for reducing energy in the gases. At least one vent valve is disposed downstream of the at least one decompression chamber for expelling the gases into the atmosphere. A mounting system and a mounting method are also provided.