FX Impact .25 regulator setting

a8cdbc998327cb6b05e9c771fbd6dcbf.jpg
 
Is there a better gauge that I could use for accurately setting the reg pressure? 

I would assume that I could unscrew the gauge if the rifle is depressurized and use a larger gauge while setting the pressure and then depressurize again and put the old gauge back.

It's so hard to guess the position of the needle relative to the actual pressure and if I go over then I have to depressurize and start over again.