Takes a while to load - but HPR & LPR adjustment is covered on pages 21 & 22
One of the guys in our team runs a BKO which is similar. I think he adjusts LPR until the gun cycles & re-cocks reliably, and then fine tunes the HPR to get the velocity spot on? His needs an allen key for the LPR (under front of barrel) but Promasters have a slotted adjuster that you can turn with a coin
its changed by adjusting the HPR allen screw (the bottom of the reg) and the LPR (rotating the thing under the barrel with either a coin, or that plastic disk thing)