when using any high solids primer or even epoxy you need to keep the gun rinsed. if left in gun during flash time the solids will collect in the nozzle . this will slowly shut down the flow. ever seem like the second or third coat goes on dry ?? this is a trick i came up with years ago when i started using gravity guns.
get a ketchup bottle or something similar . i bought these by the box back when i was doing more custom work and using my airbrush for colors.
after a coat i empty the cup , wipe it out with a paper towel then insert the bottle full of thinner. pull the trigger wide open and flush the nozzle good. now i have a clean head ready for the next coat.
just food for thought and worth exactly what you paid for it . :encouragement: