The MP5K was apparently set to be Half-Life 2's primary SMG. At some point during the game's development, the MP5K and its replacement, the H&K MP7, existed side-by-side, but in the end it was cut in favor of the MP7.
By the time the Beta was leaked, the viewmodel for the MP5K had been deleted and replaced with that of the final SMG.
Based on how the SMG1 behaves in the Beta, it seems that the MP5K would be more accurate out of the two SMGs. In addition, it would have a lower rate of fire than the SMG2. It uses medium rounds, which are also used in the OICW and AK-47.
Behind the scenes
- The MP5K appears to have been scrapped before the E3 2003 presentation; during the "Lab" presentation, Alyx gives the MP5K to Freeman, but the final SMG appears in his hands.
- As seen in e3_c17_01 and e3_c17_02 both citizens and Barney Calhoun as well as others were to still use the MP5K until late 2003 in development of Half-Life 2. It was most likely a placeholder though still used the exact same sound files of the MP5K. The MP5K was even used by combine soldiers as well as others.
- In the Half-Life 2 files, several texture files for HUD weapon icons can be found, most of which still containing the icons for almost all of the cut weapons. The MP5K is among them. It is also present in the font "HLHUD.ttf", originally used for all the HUD glyphs but incomplete at the time of the leak. It was replaced by "HalfLife2.ttf" in the final game, but the MP5K icon is not present anymore.
- The food package given by the Combine Dispenser works as a weapon, with an entity, since it technically works as a weapon for the Citizen NPCs. Typing the command "
give weapon_citizenpackage" into the console gives the package worldmodel. The HUD icon to appear after spawning is that of the MP5K, with "SMG1" above.