Airsoft guns shoot non-metallic spherical projectiles, commonly known as BBs, which are made of plastic and are 6mm in diameter. The velocity at which airsoft guns shoot these BBs can vary depending on the type of gun and its design mechanism for pellet propulsion. For example, low-end spring pistols can shoot BBs at velocities of 30 m/s (98 ft/s), while heavily upgraded customized guns can shoot BBs at velocities of up to 200 m/s (660 ft/s) . Airsoft guns can be categorized into two groups based on their design mechanism for pellet propulsion: mechanical and pneumatic. Mechanical airsoft guns consist of a coil spring-loaded piston air pump that is either manually cocked (e.g. spring guns) or automatically cycled by a battery-powered electric motor gearbox (e.g. AEGs). Pneumatic airsoft guns operate by valve-controlled release of prefilled bottled gas such as compressed propane mixed with silicone oil (commonly known as "Green Gas") or CO2 canisters (e.g. GBB guns) .

In summary, airsoft guns shoot plastic BBs that are 6mm in diameter, and the velocity at which they shoot can vary depending on the type of gun and its design mechanism for pellet propulsion.