A Semi-automatic rifle is a rifle that fires one round each time the trigger is pulled. During World War II, Germany and the Soviet Union deployed semi-automatic rifles in limited scales, while the United States deployed the semi-automatic M1 Garand as their main service rifle. Semi-automatic rifles are generally used where accuracy is important for taking out targets rather than rapid firing and giving away one's position. Selective fire modes often include semi-automatic fire. The semi-automatic function is also a feature on battle rifles, and some sniper rifles. Generally, semi-automatic rifles have high power, but a low fire rate, in comparison to other weapons. Some people have built controllers which push the fire button much quicker than a human could, achieving deadly, though morally questionable, results (commonly called "mods"). Before using a semi-automatic weapon, one should take into consideration whether it has a Firecap or not. A firecap determines its maximum rate of fire.
In the first games, from Call of Duty to Call of Duty: Roads to Victory, semi-automatic rifles have their own weapon class. This is not the case in any following games starting from Call of Duty 4: Modern Warfare, where semi-automatic rifles do appear, but are classed with other fully-auto/burst assault rifles and sniper rifles. In Call of Duty: Modern Warfare II, most battle rifles start out in the semi-auto fire mode and can switch to another mode. Several weapons also have altered damage values depending on their selected fire mode.