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.
Spring-powered airsoft guns are generally not as powerful as gas but are more powerful than electric models, although some spring shotguns and bolt-action rifles can be very powerful and shoot at velocities of 400â700 ft/s (120â210 m/s).