Pressure range limited on my water pressure

I have a Square D Class 9013 Ser B Type FSG 2 Pumptrol Pressure switch (its cut-on/cut off range is supposed to be 30/50) and my water pressure range is limited to a range of 28 turn on and 30 lbs. turn off. I turned the #1 screw a few turns and my #2 screw till it almost bottoms out the spring and now my range has increase to about 30 turn on and 32 turn off. I was wondering why I can't get a higher turn off pressure. Is it possible my pressure tank has very little air in it. I checked the pressure in the tank and it was the same as on the pressure gauge at the time which was 32 #'s. What do I need to do to increase the pressure?

Thanks dhilgy214