A review on the physiology of Insulin like Growth Factor-I (IGF-I) ... by Debnath, Surajit / Advances in Environmental Biology.
The spring piston airgun generates power using a powerful spring-loaded piston that is housed within a compression chamber. Cocking the gun (using a break barrel, side lever, or under lever mechanism) causes the piston assembly to compress the spring. When the spring is released it pushes the piston forward compressing a column of air in the chamber behind the pellet.
A pump piston is a moving component that uses piston rings to create a seal, and transfers force in order to eject or compress fluid in the cylinder. Reciprocating pumps are either duplex (two cylinders) or triplex (three cylinders). These pumps may be powered by steam or air, or via a motor or engine's belt drive.