The Glock 18 is a selective-fire (which means it can fire either semi-automatic or full automatic mode), polymer-framed 9x19mm Parabellum pistol. It is based on the Glock 17, but unlike the Glock 17, it can fire in full automatic mode. It normally holds 33-round box magazines and it fires 1,200 rounds per minute. In other words, the gun fires so quickly that it is impossible to fire single shots when in full automatic mode. While it is light enough to fire with one hand, it is not a good idea because its fast rate of fire makes the gun kick back a lot.