Has anyone used this to paint inside of rockers with?

I have a cheep schutz gun with the 3m 36″ 360° wand and tried to spray zero rust and POR-15 and am not having any luck getting it to spray a consistent pattern. If anyone has a sure bet that works well please advise or PM me as I need to do this this week or weekend and need to procure a product that will work. I would like to be able to spray both POR15 and Zero Rust and Eastwood products with it if possible. If I need more than one solution so be it.
Thanks