Over in the Garry's Mod forum, somebody released some of the Beta models.
This pack included a bunch of guns and items left out from the Beta, and it included the Gauss Gun. But, One was Red, Titled "Gauss Gun", and one was blue, titled "Super Gauss Gun". The red and blue parts do indeed look like the red and blue gravity gun. But, these guns were built by rebels and there material options are very limited. Perhaps, the orange part is the power supply? Because when you charge up the gun, the orange parts move and then release a huge burst of energy.
actually i meant when you go to thirdperson view with the gauss gun, it looks so much similiar to the gravity gun...
btw, why is the thread moved? i remember i posted it in rumors...
Maybe these guns were built around the same technology. Dr.Vance probably saw the gauss gun and started modifing it till it became the gravity gun. What do you think.