Magazine (1) for a firearm, in particular for a semiautomatic CO2 or compressed-air firearm, comprising a basic magazine body, a number of projectile supports (2) for the reception of projectiles (3) as well as a transport means for the projectile supports, whereas the transport means is designed for receiving the projectile supports (2) movably with respect to the basic magazine body, whereas the transport means is designed for moving the projectile supports (2) in a circuit, whereas the transport means has at least one endless transport belt (4), whereas the projectile supports (2) are connected to the transport belt (4).