RE: Do I have to wrong mix nozzle?
These are what you need:
74695A12 Bayonet Mixer Nozzle 5.9" Long 1/4" Taper Tip For Duo-Pak Dispensing Cartridge Gun and Mixer
74695A57 Bayonet Mixer Nozzle 3.4" Long 3/16" Taper Tip For Duo-Pak Dispensing Cartridge Gun and Mixer