A suppressor mechanism has an elongate tubular housing containing baffles and into which is assembled a suppressor mount body having spaced thread sections and spaced tapered gas seal surfaces. An adapter/muzzle brake member defines an internally threaded section that establishes threaded connection with the reduced diameter externally threaded section of a typical firearm barrel that is prepared for attachment of a suppressor thereto. The suppressor mount body and the muzzle brake/adapter member each define spaced threaded sections that establish threaded connection and promote enhanced structural integrity. The spaced internal tapered surfaces of the suppressor mount body and the spaced external tapered surfaces of the muzzle brake/adapter member establish spaced internal cartridge gas seals that prevent high pressure hot cartridge gas and gunpowder residue from coming into contact with and potentially fouling the thread connections of the suppressor mount body and the muzzle brake/adapter member.