Airsoft Guns Performance

Airsoft guns shoot 0.2 g BBs at velocities from 100 ft/s (30 m/s) for a low-end spring pistol, to 550 ft/s (170 m/s) and beyond for heavily-upgraded customized sniper rifles. Most non-upgraded AEG’s using the Tokyo Marui system are in the middle, producing velocities from 270 to 300 ft/s (80 to 90 m/s), but upgrades to the internal components can increase the pellet velocity significantly.
Hop-up & Bernoulli’s principle:
Bernoulli’s principle is a physical law that says that if a pellet is given a backspin an overpressure is formed under the bullet and an under pressure is formed on the top of the bullet. These pressures affect the bullet as on an airplanes wings a lift is formed. The bullet is sucked upwards. If the force caused by the backspin is equal to the effect of gravitation the bullet will fall slower and have a flatter trajectory, which gives the pellet longer range.
In Airsoft guns this is often implemented as a rubber piece at the rear of the barrel that is thicker at the top of the barrel than the bottom. As the pellet moves past this piece it tends to roll, inducing a backspin.