I would advise in getting a seprate gun for primer with a 1.6,1.8 or 2.0 tip.(depends on how thick your primer is, etc..) I Like to use HVLP guns and its all I can use here in california.
Now for the paint gun, I would advise in either Sata, 3M, devilbiss, or Iwata

Get a HVLP gun they work great and waste less product.

SataJet3000hvlp for a paint gun. Sata RP for a clear gun, and any $100 paint gun will be ok for primer. Sata guns are expensive but IMO The best. I've used everything else and still I go back to them.