MP5K

Not to be confused with the MP5. The M5K, in reality known as the MP5K (German: Maschinenpistole 5 Kurz, English: Machine Pistol Model 5 Short) is a variant of the German MP5 developed in the 1980's, and both weapons are produced by Heckler & Koch. The M5K fires the same 9x19 Parabellum round from the original MP5 from either 15 or 30-round magazines.

This variant was developed for counter-terrorist and law enforcement agencies that needed a large amount of firepower in a compact package. Compared to the original, the MP5K has a shorter range and penetration but is much more maneuverable to handle over the MP5 due to its smaller size. A variant of the MP5K, called the M5K PDW, was developed in the 1990's as a replacement of military sidearms for soldiers and differs by having an attached folding stock on the rear of the weapon.

Battlefield 3: Close Quarters
In Battlefield 3: Close Quarters, the M5K was spotted in the trailer for Donya Fortress in Conquest Domination, in the hands of a Russian Assault soldier. The weapon is seen with a 20-round magazine, a Red Dot Sight, a Suppressor, and a Laser Sight.

Its ballistic characteristics are similar to the PP-2000, doing similar damage but with a higher rate of fire and increased recoil. Due to these factors, engagements with the M5K should be kept at very short ranges. Burst firing can help at medium range, but the high damage drop off makes this weapon unfavourable as it will take up to 10 shots to kill an uninjured foe. The iron sights on the M5K are very clear and easy to aquire targets with at the ranges it should be used at.

To unlock the M5K players must complete the "Hold the Trigger" assignment. The requirements for this assignment are:
 * Finish top five in Gun Master (once)
 * 100 Kills with Submachine Guns