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 nitro piston air gun is a spring gun without the spring. Instead of using a coiled spring as the power plant, it uses a nitrogen-filled cylinder. The nitrogen in this cylinder is already kept under pressure and you put more pressure to it when you cock the gun.ighth, a nitro piston is more long-lasting than a spring air gun. The general rule is do not get spring compression over 50% to remain its reliability. But in the air gun world, it is not uncommon to make the compression up to 100% to maximize performance. This weakens the spring and shortens its life-span.