US Patent 9982962 Air gun with multiple energy sources

An air gun includes two different types of energy sources that may be used to fire a projectile. A first type of energy source may include an air cylinder having a piston that moves through a cylinder, as urged by a mechanical spring or gas strut, to create compressed air charge for firing a projectile. A second type of energy source may include a compressed gas storage tank that holds compressed air, or another propellant, that is released during firing to urge the piston through the air cylinder to create a compressed air charge for firing a projectile. An air gun may, additionally or alternately, include features that promote efficient delivery of a compressed air charge to a transfer port and projectile chamber, during firing. Examples of such features include piston configurations that reduce or prevent piston rebound through the interaction of the piston face and air cylinder, upon impact.