MAC-10

In game
The MAC-10 is unique to Call of Duty 4: Modern Warfare (Nintendo DS). It is basically the weapon equivalent of the Mini-Uzi from the console game. It has a 40-round magazine and a much slower rate of fire than in real life, though it is still quite fast. It's used quite often in the SAS missions, but it is not found in USMC missions until "Missile Away". It is an overall good gun because of its large magazine.

Trivia

 * Out of both of the DS games so far, the MAC-10 has the highest rate of fire. What is odd about this is that no weapons in Call of Duty: World at War can even compare to this, namely the PPSh-41.