Within the world of Code Geass, firearms are small, personal weapons used by various characters throughout the series. Unlike real-world firearms, those found in the world of Code Geass do not use gunpowder as an ammunition propellant, eliminating the need for brass casings; instead they operate by using a strong electromagnetic pulse to fire bullets. CC's flashback in Episode 25 of R1 shows a soldier carrying what appears to be a bolt-action rifle, suggesting that such weapons are a relatively recent development in the Code Geass timeline.
The most common types of firearms are pistols and automatic weapons; other small arms include Rocket Propelled Grenade launchers and flamethrowers that can be seen on occasion. Britannia's standard infantry rifle is similar to the real world FN P90, albeit having a larger size and slightly different magazine.
Knightmare Frames also possess similar weaponry, although scaled to their size; ranging from handheld assault rifles, to built-in missile pods.