I have not been able to apply Slick Sand with my old spray guns. (Fluttering fan or small poor quality fan). Can’t seem to find anything wrong with the guns. My question is what would be the optimum tip size to use for spraying Slick Sand. If I get a new gun will it take more than one size nozzle to cover primer/paint needs? I have not painted a car for more than 20 years and then only a few as do-it-yourself projects, so I have a lot to learn. Thanks for any help you can offer.