From Madness Combat Wiki

Type: Pistol
Attachment(s): Suppressor
Used by: Deimos, agents
Kill(s): 10

The H&K MK-23 is a German .45 ACP pistol that served as a basis for the USP pistol series. It appears in most episodes after Madness Combat 6: Antipathy, and is used by Deimos in Madness Combat 7.5, equipped with a suppressor, to infiltrate the compound in the beginning of the animation. Deimos fired thirteen shots before the gun is completely discharged. The gun also appears on the "Hygiene is Keen" posters.

The pistol makes it's first appearance in a Madness game, being MADNESS: Project Nexus. The weapon holds 12 rounds and can be unlocked after completing the Foundry arena level. Like most of the weapons in-game, the weapon is renamed to avoid copyright trouble(That being, the weapon is renamed to NK-45 instead of MK-23).