Overview
The MP5SD is an integrally suppressed 9mm submachine gun, a variant of the venerable Heckler & Koch MP5 weapon series. First created in 1974, the weapon features an aluminum suppressor integrated directly onto the muzzle and a lightweight bolt. Being suppressed, it is inherently quieter than other weapons, making it ideal for stealthy assaults or covert infiltrations. However, the suppressor also reduces stopping power of each individual bullet along with the effective range of the weapon. The MP5SD is used by countless militaries worldwide.
In Mercenaries series
The MP5SD (called Covert Submachine Gun) is seen in both iterations of the Mercenaries series. In World in Flames, it can only be bought from Pirate shops under the "Covert Assault Kit", at $10k per unit.
The MP5SD has the same magazine capacity as most other rifles or submachine guns, and its accuracy is roughly the same as Machine Pistols or Light Machine Gun weapons. It's real unique feature lies in its integral suppressor, which allows the player to quietly kill enemies and hopefully, not alert enemy sentries during infiltration. However, it should be noted that the MP5SD's overall lack of precision accuracy and the glitchy AI of enemies makes the suppressor null and void. Besides this, the MP5SD is no better or no worse than any other assault weapon.
In Mercenaries: Playground of Destruction the South Korean elite ROKA 707th Commando Unit soldiers and South Korean Officers seem to use this weapon the most and is the most frequent way to obtain one. Also during the Chinese mission in which you must kill the Russian officers a crate in front of the Chinese HQ contains a covert submachine gun.