Abstract: A caulking gun is disclosed comprising a handle, a ramp mounted on the handle for receiving a caulking cartridge having a nozzle thereon, the end of which has to be removed by cutting. The nozzle of the caulking gun is also sealed to a caulking cartridge by means of a ruptureable seal. An opening is provided in the handle into which the nozzle of such a caulking gun may be inserted to cut the end therefrom by means of a knife blade operably attached to a trigger used for advancing a ram to extrude caulking compound from the cartridge. The handle of the caulking gun also contains a puncturing tool retractably mounted in the handle for puncturing the seal at the base of the nozzle of the caulking cartridge.