Fake Chainguns in Transformers 2

[Rockwolf66]

Having just bought a copy of Transformers: Revenge of the Fallen, I'm wondering...Are the fake "Chainguns" on the NEST vehicles built around anything. I ask because i saw them in the first Transformers film and in this lattest film they seem to be on M1917 mounts. meaning that they look like mounts fabricated from Old M1917 tripod mounts. As they are seen to be "Fireing" in this lattest film I'd love to take a closer look at the systems.