How do you tell when you have the correct fluid tip size for the paint being sprayed. I recently purchased a Sharpe T-1 reduced pressure gun with a 1.6 mm tip, but I think it is too big as I need to turn the fluid adjustment knob in 2-3 turns to avoid getting runs. I spray mostly single stage urethanes and polyurethanes (Dupont Chroma 1 and Imron). 1.6 was the recommended tip for single stage paints, but I think I need to go smaller, maybe 1.4 or 1.3. Any suggestions? Also, what is the difference in spray pattern and finish quality between using a large tip and turning the fluid adjustment knob in and using a smaller tip with the adjustment set fully open ?