modular spacesuit rifle
The briefing on this one was funny, it had to look more like a tool and be big as it is supposed to be handled during EVAs in a heavy Spacesuit. Featuring a thick polymer casing so it can be thrown around and bump into things when hanging from the Spacesuit.
It had to use caseless ammo to avoid additional debris when used in Zero G Environments. It features a high capacity helical magazine to minimize reloads, as these can be tricky in a spacesuit too :)
There were a whole load of modules planned for it, but unfortunately the project got cancelled.