MP5

The Heckler & Koch MP5NA3 is a model in the MP5 (Maschinenpistole 5) series of submachine guns. The MP5 was first developed in 1964 and was first adopted by the German Federal Police (Bundespolizei). The MP5 has since been adopted by many police and military agencies worldwide, including the GSG-9, the GEO, the FBI, UIM, GIGN, JTF 2, the SEALs and the SAS. For that reason, the MP5 has been associated with many as the de-facto firearm for police, special operations and counter-terrorist units. It is praised for its superb accuracy for a submachine gun.

The MP5 has many different variants, ranging from a standard fixed stock and standard barrel length, to the MP5SD with an integral sound suppressor and MP5K PDW with folding stock and shortened barrel. In addition, several versions are equipped with a compact, detachable forward handgrip which further augments the gun's superior accuracy. The Navy ("N") models are primarily distinguishable by their trigger group.

In Game
In single-player, the MP5NA3 can be found frequently in the regular version, used by the USMC and Ultranationalists, in the missions Blackout, Hunted, Safehouse, One Shot, One Kill, The Sins of the Father, and No Fighting In The War Room. The suppressed version, used by the SAS, can be found in Crew Expendable, Ultimatum and Mile High Club.

In multiplayer, the MP5NA3 is the only SMG available at level 1, and can be equipped with a red dot sight, suppressor and ACOG scope. It is popular in Call of Duty 4 multiplayer because of its relatively decent accuracy and damage. Carrying the M9 as a sidearm while using the MP5NA3 will add extra ammunition to the reserve ammunition for both weapons. It is widely used by Gamebattles and in Search and Destroy matches because of the aforementioned features.

The MP5's ingame reload animation uses the bolt handle incorrectly. Instead of pulling it back and locking it in the recess above the weapon (similar to the G3A4s reload animation), the bolt is pulled back and brought forward, which is inaccurate, as the MP5's bolt is not designed for such use. It will not damage the weapon to do so, but it is hard to put in a magazine on the MP5 when the bolt is closed, reloading it correctly eliminates this problem as the bolt is open when the new magazine is inserted.

Trivia
In real life the MP5 can accept a M203 grenade launcher, even though the MP5 is quite small. However this would be pointless as the mp5 is not used as an assault weapon, more so for counter terrorist operations involving hostages.