A projectile firing gun or weapon barrel is adapted with a gas porting system having conduits and outlets specifically configured, positioned and adapted for maximizing reductions in muzzle jump and/or recoil in accordance with principles of reverse thrust. The conduits or flow tubes are contemplated to be configured to function as nozzles whereby varying the shape and size of the conduit walls can maximize the outlet velocity of gases flowing at subsonic as well as supersonic velocities and the stream of redirected gas flow can be concentrated. The system incorporates porting holes located further rearward than at the barrel muzzle, but at a proven safe distance from the barrel chamber, which porting holes are in fluid communication with gas conduits/nozzles. Such conduit/nozzle openings redirect in a specific upwardly direction and concentrate a vented stream of high velocity expanding gas generated upon firing of the gun or weapon so as to maximize the generation of downward thrust forces to overcome muzzle jump. Similarly, such conduit/nozzle openings redirect rearward and concentrate a vented stream of high velocity expanding gas generated upon firing of the gun or weapon so as to maximize the generation of forward thrust forces to overcome felt recoil. Venting the explosion gases further rearward than at the barrel muzzle maximizes the duration of thrust forces as gases are vented well prior to the projectile exiting the barrel and utilizes gas forces greater than that available after the projectile has exited the barrel.