Male Cast GM GAS guide?

So i have a 180 Cast GM (Male) that has nothing GASed yet. I was wondering if there is any guides out there or if anybody can tell me how to GAS for the most damage.
Please reply! Thanks!!

The most Damage you can do is Shotgun Damage hands down. First Gas strengh to the max. Then Gas everthing related to shotgun. Element, critical. No class can do runs faster than a Gunmaster with GASed shotgun.

My character is Vultron. I am totally Gased for Gunmaster shotgun damage and Guntecher Machinegun damage. I do the most Shotgun damage and Machine gun damage possible in the game.