We had the really industrial strength Hilti guns in the Navy. We used them for Damage Control (when you have a hole in the ship and water's coming in, you want to stick a patch on really quickly). Those things could shoot a fastener most of the way through 2 quarter inch steel plates. The fasteners we used look like a cross between a bullet and a machine screw. The bullet portion punches through the steel and the screw threads hold it in place. Really hardcore ship-nailing guns : )