A low pressure air gun (10,100) for seismic exploration which reduces high frequency sounds, comprising: - a cylindrical housing; - a backbone vacuum brazed permanently in place on top of and to reinforce the cylindrical housing and serve as a flat mounting surface for a solenoid operated air gun firing valve; - a bulkhead wall within the cylindrical housing to separate an operating chamber (30,130) from an air cushion chamber; - a central opening in the bulkhead wall; - a shuttle assembly having a shaft (27,127) inserted through the central opening in the bulkhead wall and having an operating flange (29,129) on an end of the shaft (27,127) within the operating chamber (30 130); - a firing chamber secured to the cylindrical housing; - a cup shaped firing piston secured to an opposing end of the shuttle assembly shaft separating the air cushion chamber from the firing chamber; - a plurality of ports formed within the cylindrical housing in the firing chamber, characterized in that the low pressure air gun comprises: - a sliding firing seal, held securely between a contoured spring loaded back ring and a contoured shoulder of the housing, and configured to, in a firing position of the cup shaped firing piston before the triggering of the air gun, seal the outside diameter of the cup shaped firing piston to retain the air within the firing chamber, until that, when the air gun is triggered, the cup shaped firing piston moves and an end surface of the cup clears an edge of each port; and in that a recess is formed along the entire internal circumference of the cylindrical housing, said recess having the same height and the same position in the axial direction of the cylindrical housing as said plurality of ports, so that, in the section of the cylindrical housing wherein said plurality of ports is located, an internal diameter of the cylindrical housing, considered in a direction that is perpendicular to said flat mounting surface for the solenoid operated air gun firing valve, is larger than the outer diameter of the cup shaped firing piston,and wherein the air gun (10,100) operates at pressures in a range of 400 psi, namely 27.6 bar, to 1000 psi, namely 68.9 bar. - a cylindrical housing; - a backbone vacuum brazed permanently in place on top of and to reinforce the cylindrical housing and serve as a flat mounting surface for a solenoid operated air gun firing valve; - a bulkhead wall within the cylindrical housing to separate an operating chamber (30,130) from an air cushion chamber; - a central opening in the bulkhead wall; - a shuttle assembly having a shaft (27,127) inserted through the central opening in the bulkhead wall and having an operating flange (29,129) on an end of the shaft (27,127) within the operating chamber (30 130); - a firing chamber secured to the cylindrical housing; - a cup shaped firing piston secured to an opposing end of the shuttle assembly shaft separating the air cushion chamber from the firing chamber; - a plurality of ports formed within the cylindrical housing in the firing chamber, characterized in that the low pressure air gun comprises: - a sliding firing seal, held securely between a contoured spring loaded back ring and a contoured shoulder of the housing, and configured to, in a firing position of the cup shaped firing piston before the triggering of the air gun, seal the outside diameter of the cup shaped firing piston to retain the air within the firing chamber, until that, when the air gun is triggered, the cup shaped firing piston moves and an end surface of the cup clears an edge of each port; and in that a recess is formed along the entire internal circumference of the cylindrical housing, said recess having the same height and the same position in the axial direction of the cylindrical housing as said plurality of ports, so that, in the section of the cylindrical housing wherein said plurality of ports is located, an internal diameter of the cylindrical housing, considered in a direction that is perpendicular to said flat mounting surface for the solenoid operated air gun firing valve, is larger than the outer diameter of the cup shaped firing piston,and wherein the air gun (10,100) operates at pressures in a range of 400 psi, namely 27.6 bar, to 1000 psi, namely 68.9 bar.