SKS

The SKS is a Rifle featured in Call of Duty: Black Ops (Nintendo DS) and Call of Duty: Modern Warfare 3: Defiance.

Call of Duty: Black Ops
In Black ops, it has a 30 round magazine, low recoil, is fully automatic (semiautomatic in multiplayer however) and is used primarily by the Afghan fighters in singleplayer and the enemy factions in multiplayer. It can be found in the mystery box in zombies, like every other weapon except the RPG, the M72 LAW and the Explosive Tip Crossbow.

Call of Duty: Modern Warfare 3: Defiance
The SKS appears again in Call of Duty: Modern Warfare 3: Defiance. It has a 10 round magazine, is semi-automatic only, and has slightly more power than assault rifles, but still less than sniper rifles.

Trivia

 * The SKS is the only Semiautomatic rifle in multiplayer, making it highly coveted and favoured in Rifle matches.