This stationary automatic machine gun looks much like a M41 LAAG, except removed from it's Warthog base. The M41 is meant to be a light anti-aircraft gun (hence LAAG), but is also devastating against ground troops. This stationary gun features an endless ammo supply as well.
Good; however, it seems you tried to add more detail than what existed in game. Also, THIS is a HMG (Heavy Machine Gun) the LAAG is a triple barreled rotary gun found only on the Warthog, the HMG also fires 7.62mm (.30cal) rounds as opposed to the LAAG's 12.7mm (.50cal). Good though.