Pneumatic airguns use compressed air for power. The air compressed in the airgun depends on the type of pneumatic it is. The most common pneumatic airgun is the multi-stroke, or sometimes called pump-up type pneumatic airgun. The tiny bit of air compressed in a multi-stroke pneumatic takes as between two and ten strokes of the forend pump lever to get the internal pressure needed to power the pellet out the barrel at a decent pace. Most multi-stroke pneumatic airguns are compact, recoilless and light weight. Multi-stroke pneumatics are moderate in power. As you pump up the multi-stroke airgun each progressive pump takes more effort. Accuracy from a multi-stroke is okay, but there are too many variables in the pumping procedure to allow for stellar performance.
A more preferable form of pneumatic is the single stroke pneumatic airgun. As the name implies, one motion of the cocking lever is all that is needed to compress the air for propulsion. The single stoke format is used on many high end 10 meter match airguns, such as the Beeman/FWB 601. Consistency, accuracy and lack of recoil are the reasons top shooters gravitate to this type of power plant. The downside is low power, but with tack driving accuracy at close range, is the reason 10 meter shooters love them.