How does a PCP airgun work?

A PCP stores high-pressure air (typically 2,000 to 4,500 PSI) in an onboard reservoir or removable bottle.

When you pull the trigger, a hammer strikes a valve that opens for a fraction of a second, releasing a precisely metered burst of air behind the pellet. Because only air moves at firing, recoil is minimal, the lock time is short, and accuracy potential is very high. Once the reservoir runs low, you refill from a hand pump, scuba/SCBA tank, or HPA compressor.