Caulking gun for dispensing viscous material comprising • a stock formed with a central transverse aperture, • a cartridge keep, • a push rod longitudinally moveably mounted in the stock provided at its one end with a plunger which engages the piston of a cartridge placed in the cartridge keep, • push means for engaging the push rod to advance it, the push means being pivotably held between the flanks on a trigger and being biased rearwards into an engaged attitude with the push rod by means of a spring, • the trigger being coupled to the push means, • brake means hinged to the stock and provided with a clearance hole for engaging the push rod such that the push rod is moveable in a direction advancing the push rod towards the cartridge and is held in a direction retreating the push rod from the cartridge, which brake means are arranged to travel to a first position relative to the stock as the push rod advances and to a second position as the push rod retreats thereby defining the retreat of the push rod, wherein the brake means are in the first and in the second position inclined relative to the axis of the push rod and release means are provided for pushing the brake means in a third, essentially perpendicular position relative to the axis of the push rod in order to disengage the push rod from the brake means for pulling back the push rod and for acting simultaneously on the push means in order to disengage the push rod, and • adjusting means (15, 16) arranged for varying the retreat of the push rod, characterized in that wherein the release means are configured as a lever which is coupled to a back part extending over the spring means and ending behind the push means, which when it is activated pushes one end of the brake means from the inclined position to the essentially perpendicular position in which the push rod can be pulled back and acts simultaneously on the push means in order to disengage the push rod, wherein the adjusting means (15, 16), the brake means and the release means are arranged in the aperture of the stock above the trigger. • a stock formed with a central transverse aperture, • a cartridge keep, • a push rod longitudinally moveably mounted in the stock provided at its one end with a plunger which engages the piston of a cartridge placed in the cartridge keep, • push means for engaging the push rod to advance it, the push means being pivotably held between the flanks on a trigger and being biased rearwards into an engaged attitude with the push rod by means of a spring, • the trigger being coupled to the push means, • brake means hinged to the stock and provided with a clearance hole for engaging the push rod such that the push rod is moveable in a direction advancing the push rod towards the cartridge and is held in a direction retreating the push rod from the cartridge, which brake means are arranged to travel to a first position relative to the stock as the push rod advances and to a second position as the push rod retreats thereby defining the retreat of the push rod, wherein the brake means are in the first and in the second position inclined relative to the axis of the push rod and release means are provided for pushing the brake means in a third, essentially perpendicular position relative to the axis of the push rod in order to disengage the push rod from the brake means for pulling back the push rod and for acting simultaneously on the push means in order to disengage the push rod, and • adjusting means (15, 16) arranged for varying the retreat of the push rod,