The MP5 PIP has some interesting features, including a weaver-style top rail, a “chute” type magazine well, a centrally located button that appears to be a bolt catch/release, and a round magazine catch. Also, the MP5 PIP appears to be the origin for the distinctive “flipper” charging handle of eventually used in the G36.
Ultimately the PIP would stay a prototype but some features from the design would go on to be in other later HK designs like the UMP.
Not Ian’s video but this guy is the guy on Heckler and Koch stuff: [14:13] https://youtu.be/tLi05QgleTw?si=
No clue about how the actual ergonomics of handling this boxy thing would be in comparison to say an MP5k, but damn if this is not the pinnacle of 80s retro futuristic weapon design.
Something like this with slight changes amd basically a blinky light or two would so perfectly fit into a kind of cyberpunk / spy thriller / alt history kind of setting, like an expansion of the RoboCop universe or something.