makelures

I use Autoair paints because I've found them better than both createx and wicked (yes, I know they're all made by the smae company    ).
 
First advice: don't thin with water, windex or anything else other than the manufacturers reducer. The reducer contains a mild solvent that helps keep the paint from drying on the tip of the airbrush. Water obviously doesn't have this, windex and other solvents have additives that can cause comaptibility issues later. You spent enough on an airbrush and quality paint, don't try and save a few bucks on reducer or the money you already spent is wasted!
 
Second: Badger airbrush should be fine for the job. If your airbrush is clean and you're getting a grainy texture then it's an atomization issue. Assuming there are no small lumps to block the airbrush nozzle then it comes down to dilution and air pressure. This is different for every airbrush and every paint, so I can't give you hard and fast rule. But as an example, I only go down to 5 psi for fine detail work and with my Iwata airbrush I'll generally use a paint:reducer ratio of 50:50 for transparent paints, 40:60 for opaques and 30:70 for pearls or metallics. More often I'll work with slightly thicker paint (maybe 60:40) and higher air pressures (up to 35 psi).
 
It sounds to me like you need to reduce your paint more and/or bump up your air pressures. I'd start by thinning the paint 50:50 and then play with the air pressure until it's going on smooth.
 
Hope this helps