I got the gun yesterday and fired it up today. There is an adjustable knurled knib around the trigger that apparently adjusts the force, but it seems to work only when turned fully clockwise.
In any case I tried it out on one of the lugnuts on my Jeep. Wouldn't budge it (torques to 100 ft-lbs). I'm pi$$ed. When I walk over to my compressor I see the regulator is set to 40psi. Cranked it back up to 90, and no problems.
Now I need to see if the problem with the cheap wrench was also due to lack of air pressure.