A gun barrel sound suppressor incorporating a housing having a breach end, a muzzle end, and a barrel axis extending between those ends; a bullet passage conduit aligned with the barrel axis; a first annular gas outlet port opening the bullet passage conduit; a first annular gas inlet port further opening the bullet passage conduit, the first annular gas inlet port being positioned muzzlewardly from the first annular gas outlet port; a first circumferentially extending “U” channel having a web, having a breachward arm having a distal end, and having a muzzleward arm having a distal end, wherein the distal end of the first breachward arm communicates with the first annular gas outlet port, and wherein the distal end of the first muzzleward arm communicates with the first annular gas inlet port.