PCP newbie question

Scenario: my regulator is set to 125 bar and my HST to about 95% of max velocity, I fill my PCP to the max 250 bar, I shoot a bunch and now I'm down to 150 bar, How close to the regulator setting can I safely/effectively/efficiently empty the air tube of my PCP? Can I safely shoot all the way down to the regulator setting? Thank you!
Going below the Reg pressure is called falling off the Reg. you can keep going but consistency will not be there.....sometimes. Give it a try, take notes and see what happens, you won't break anything that I know of.