You have said that you are not using the regulator, but only your gauge set up. But, You are unscrewing the gauge set up to simulate the effect of using shims with the regulator. So actually, the Ninja regulator has nothing to do with your observations, Only the use of shims with your test gauge. (and actually not even those as you only simulate the shimmed position)
I can follow that now that I have typed it
Can you be sure that the tank opening pin interface of your gauge set up is "eggs-actly" the same as the pin interface on the regulator?
Perhaps there is some variation.
"The mind complicates the simple truth"