Firearm sound suppressor apparatus comprising a sound suppressor body including a sound suppressing front section and a back section, the back section adapted to coaxially receive a muzzle fixture secured to the firearm, the back section configured with at least three interrelated chambers when the muzzle fixture is received by the back section for effecting energy attenuation of at least a portion of combustion gases exiting the muzzle fixture from the firing of the firearm.