The sniper rifle is also fairly effective against the heavy trandos. Have him shoot at your squadmates while you zoom in and kill him.
Anyone else noticed how when you zoom in with the sniper rifle, it takes one head shot, helmet or no, to kill a trando but without zooming, it takes two shots to kill a trando with a helmet?
I prefer to club with the shotgun. It's a bit reminiscient of how I enjoyed clubbing with my rifle in Call of Duty.