The design of the Slayer is based off of a mix of the AK-47, the fictional space marine bolter. It is large and simple to use. It has a massive 25mm by 75mm bullet which makes it effective against both heavily armored enemies and soft enemies.
It uses a high powered gas tap system to prevent overheating and jamming. It's inner workings are built slightly looser then a normal assult rifle, making it even more reliable. Its thick heat shield makes it perfect for the brutal combat that the LOA marines fight in.
The whole weapon is oversized to fit the muh larger Marine. It is far too large for a normal human to wield to any affect. It however lacks a buttstock as marine armor is too bulky for it to be of any use, also a buttstock is not needed at the armor is also meant to absorb the recoil of the gun.