A firearm suppressor (1) also known as a moderator includes a number of coaxially joined steel baffles (20,40,60) for dissipating discharge gasses. Each baffle can have an internal funnel structure (30) having a central aperture (31) through which the firearm projectile passes. Adjacent funnel structures form interconnected primary and secondary chambers connected by a port (28) through a flange (37) separating the chambers. A notch (36) in the central aperture of one funnel structure directs flow toward the port (48) on the diametrically opposite side of the next funnel structure. A radial hole (29) through the funnel structure connects successive primary and secondary chambers. The flange is axially located to be radially inward from an overlapping joint between two adjacent baffles in order to provide structural support to the joint.