That precludes that PCP's operate as DUMP guns ... which they do not !Dump being such as a POWDER CHARGE and all of its created energy / pressure expelling during said shot cycle.The reason behind LARGE PLENUMS in a PCP is based on the Energy / Pressure used is just a Portion or Sip of whats available. With that sip you lose not only volume but pressure being the regulator simply Can Not supply air volume or pressure to replace whats used quickly enough. So .... MORE PLENUM volume has the "Average pressure maintained" during shot remaining higher due to the volume offered by the larger plenum Simply put ...Scott S