A spring-piston is a type of air gun mechanism that uses a coiled spring to compress air and propel a projectile, typically a pellet. When the shooter pulls the trigger, the spring is released, pushing a piston forward. This action compresses the air in a chamber, creating pressure that forces the pellet out of the barrel. This design is common in many types of air rifles and pistols, offering a simple and reliable way to achieve consistent shooting performance. Spring-piston guns are often favored for target shooting and small game hunting due to their accuracy and ease of use.