So to put it simply, the new external reg is awesome.
You’ll need a pair of split ring pliers to do this.
To increase reg pressure, turn black ring clockwise.
To decrease reg pressure, turn black ring counter-clockwise.
IF DECREASING PRESSURE, TURN IT SLOWLY BY A FEW MINUTES ON A CLOCK FACE AND DRY FIRE THE GUN 2-4 TIMES, THEN TAKE A VELOCITY READING. DO THIS REPEATEDLY UNTIL YOU REACH YOUR DESIRED VELOCITY.
To safely increase/decrease reg pressure, I turn mine about no more than 5 min on a clock face. The smaller the increments of change, the more precise the fine tuning.
I personally tuned mine for accuracy. Shot a group, adjusted reg, shot another group, until I reached my desired accuracy. Then I shot it over the chrony to find out velocity.