The MP5 was developed in the 1960s by a group of engineers from the West German arms manufacturer Heckler & Koch GmbH (HK). The company, motivated by the success of the Heckler & Koch G3 rifle developed a group of small arms consisting of four types of firearms (all based on the G3 design layout), where the first type was chambered in 7.62 x 51 mm NATO, the second – using the 7.62 x 39 mm M43 round, third – the intermediate 5.56 x 45 mm NATO caliber and the fourth type – chambering the 9 x 19 mm Parabellum pistol cartridge. The MP5 (short for Maschinenpistole 5) was created within the fourth group of firearms, initially known as the HK54.
In game
Each MP5 rendition has a variant in the GTA games. GTA Vice City and San Andreas feature a MP5A3. GTA Liberty City Stories features the MP5K which looks a little lengthier than the other renditions and in Vice City Stories, the SP89 (civilian version of the MP5K) makes an appearance. In GTA IV, the MP5 is heavily modified and resembles the look of a MP10. In GTA Chinatown Wars the MP5 is called the SMG just like any other rendition, and is an arguably a better substitute for the Micro SMG, holding a better rate of fire and more damage per round. All of the MP5 renditions hold 30 rounds per magazine.
Ocean Beach - At the pier of the marina near the boats docked.
GTA IV
The SMG can be purchased at the back-alley gun shops for $2500 and each additional magazine costs $150. It can be purchased from Little Jacob for $1750 and each additional magazine will cost $20.
Schottler - Can be found on an air-conditioning ductwork in an alley between Boone St and Dillon St. This pickup is tricky to get to: the player can reach it by scaling the wooden fence on the Boone St side and following the ductwork there.
Acter Industrial Park - Can be found on the seventh floor of an observation platform of a RON Oil refinery on the southern side of the island. This is a particularly long way to go to get this weapon, however, and is not recommended.
Trivia
Both sides of GTA IV's MP5s feature "MADE IN SCOTLAND" markings (mirrored on the left side), alluding to GTA IV's Scottish developer Rockstar North.