Steamgun

A rudimentary design from an era where weapons were expected to serve multiple purposes, the steamgun is an assault rifle built from a mixture of iron and copper parts. It has a rather standard design in terms of it's body shape – a triangular stock with a hole in the center of it to make the gun lighter, a large body and extended barrel with a built in silencer. It has an under-barrel attachment which allows the use of most standard-sized knives as bayonets.. It's name comes from it's ability to harness incredibly hot steam as a weapon. Essentially, the gun has a waterline of cool water running through it – upon rapid firing the gun heats up incredibly quickly, leading to the water heating up and producing steam. The steam travels to a small, ovular compartment that sits just off to the right of the gun. Said compartment keeps the steam as hot as possible for as long as possible. The barrel of the steamgun has two holes – one for it's ammunition and another for the steam. Once enough steam has gathered (or even before) the user can vent the steam by hitting a small button on the side of the gun with their pointer finger. This causes the steam to suddenly shoot from the front of the weapon – oftentimes hot enough to cause burns if turned on an opponent.   This weapon was phased out due to the necessity of constantly refilling the cooling compartment with water. The cooling compartment is on the top of the gun, which also lead to issues with sighting and accuracy. Because of this the weapon was only ever used in very short range engagements. The steam also constantly had to be vented, and because of this it was common practice to aim the gun into the air and let the steam vent instead of using the steam to burn nearby enemies as intended. It's still popular on a few planets where close-range room clearing is a necessity, but for the most part has been forgotten by “modernized” militaries.