Model three of four, and where I pushed my rigging practice even further with a reverse joint leg system, ammo belt and toes. While a reverse leg joint system isn't the most practical or useful, I had been playing a lot of Armored Core and thought it looked cool, which usually I place above being practical (within reason though).
The original design was just a gun with legs but then I wanted to have a little more flair with ammo belts hanging off of it versus a very closed system such as a ammo box on the back.