A projectile launching device includes a receiver, an ammunition magazine, and a trap. The receiver has a magazine receiving port, a loading chamber, and a launching mechanism configured to launch a projectile via pressurized gas. The ammunition magazine has a projectile supply port and stores projectiles. The projectile supply port can be inserted into the magazine receiving port for supplying projectiles. The trap, which is located in the vicinity of the loading chamber and magazine receiving port, is oriented in a trap orientation which prevents projectile from leaving the loading chamber when the ammunition magazine is removed from the receiver.