What does FPS mean?
FPS stands for feet per second, ultimately it’s the speed of the fired projectile. In the case of airsoft, the projectile is a 6mm BB.
How does FPS affect my BBs?
Once the BB leaves the muzzle of the gun, the FPS decreases. The more FPS, the more joules (or energy), is carried with the BB, causing it to travel faster through the air, thus making it travel farther.
Weight vs. FPS.
The most common weights of BBs used for airsoft are 0.20, 0.23, and 0.25 grams. The heavier the weight of the BB, the lower the FPS. The lighter the BB the more the FPS is increased! Heavier BBs can add range and accuracy. Also, they are less susceptible to wind, which affects flight. It’s best to increase the weight of the BB as the FPS increases. Doing so will ensure your BBs perform well in your gun in regards to range and accuracy. Using heavier BBs does not change the joules carried by the BB.
Recommended BB weights.
0.20g = 250-300 FPS
0.23g = 300-350 FPS
0.25g = 350-450 FPS
Many thanks to the 73th S.A.G. for the photos