Algodoo

Uses 1x2-3.5m ASxs bullets as ammo. while not working if not kept Scruptously clean, it is rugged enough.
press enter or pull the trigger to fire(you can hold to keep firing, but DO NOT DO IT, as it tends to jam the weapon quickly).

the G11 was the closest design from the gun itself i could find. still, it's not caseless, so, sorry.

also, reloading can be a bit tricky

EDIT: for some reason a spring's length messed up. hope this quickedit fixes it