Abstract: A dispenser gun having a hollow tubular body member for receiving a cartridge of flowable material therein, and a removable cap member to maintain the cartridge within the body member so that a nozzle of the cartridge extends through an opening in the cap member. The body member includes a trigger mechanism for acting upon a cam retaining mechanism to disengage a cable into a released position to allow a spring biased pressure disc, which is connected to the cable, to act upon the cartridge to dispense or discharge the flowable material therefrom. In the non-discharging position, the cam retaining mechanism engages the cable in a locked position so that the cable prevents any forward movement of the pressure disc against the cartridge. The cartridge can be of either the disposable type or the reusable type, where a liquid impermeable insert bag can be inserted within the reusable type cartridge.