The MK32 is available in the mission "Struck Down", equipped with a Holographic Sight, and it is semi-automatic. In the beginning of the level, the Semtex grenades fired on enemy vehicles do not explode directly, being blown up using a detonator instead. However after this part, the fired grenades explode instantly after sticking to a surface, almost like normal impact grenades. Furthermore, the grenades have a "safe distance", unlike in multiplayer and Extinction.
The MK32 is purchasable as a secondary weapon. It does not have sights. Instead, the screen zooms in slightly. It fires two Semtex grenades at a time, and has six rounds loaded per cylinder. The rounds fired by the MK32 count towards Semtex challenges. Furthermore, it cannot be reloaded mid magazine, though this doesn't matter as it only comes with one magazine to start and magazines cannot be scaveneged or added with Fully Loaded or Scavenger. The two shots it fires recoil considerably, making it hard to get the two shots in the same place. Moving the aim down while the weapon is firing may help. Overall, this weapon is best used to clear or capture objective points from enemies, or to remove a camping enemy from a short distance.
The MK32 Launcher appears in Extinction under the Equalizer category. Unlike its campaign and multiplayer versions, it fires normal impact grenades instead of Semtex ones. When fully upgraded, its name becomes the MK32 Flame Rounds.