Machine gun is a general term used to describe several types of firearms which shoot projectiles for as long as the operator depresses the trigger, or until the magazine is empty. These firearms use a different fire-control group and different internal parts than their semi-automatic equivalents, and different guns may use different systems to cycle the action, such as the delayed-blowback system found in the MP5, or the gas-piston system found in the AK-47. There are classifications of machine guns; submachine guns (like Uzi's and Micro SMG's), assault rifles (like the M16 and AK-47), and "true" machine-guns (crew-served weapons like the Browning .30-cal or the M2 Browning .50-cal, which are not featured in the GTA games; however, the M-60 is featured in Grand Theft Auto: Vice City as it can be used by a single person.) This is a unique type of firearm, because the faster the cyclic rate, the faster it can send rounds downrange and increase the chance of eliminating enemies, gangs, cops, or even civilians.