It is considered to be one of the finest weapons in the world. The single shot is acceptable, instantly obsoleting the Colt 6520 pistol, and the burst mode is excellent. The MP9 is easy to control, and can dish out more punishment than other firearms in its size category. Consequently, it is highly popular among people requiring a powerful, but compact source of firepower with low maintenance requirements. This weapon is popular with freelance mercs as it can spew death at close range. It is an excellent weapon early in the game and can shred unarmored foes, a single burst able to kill even enemies in leather armor. It is very deadly at close range. Ammo can be found almost anywhere.
Ian and Sulik are very deadly with these. It is the only burst weapon Ian can use, and the first SMG players are likely to find for Sulik.
A storage room on 3rd floor in Vault 15, near the cave-in.