ofcourse the AK-47 is the best "ass-rifle " throout history.
Have you seen the movie "The sum of all Fears" when the plaines is attacking the Hangarship?
The minigun who shots ...well...trying to shoot down all the missiles...thats a gun...:D
there you have your metalfuturegun...
but i use the HK MSG90...
MSG90 Technical Specifications
Caliber 7.62x51mm (.308 )
Modes of fire Semi-automatic
Ammunition feed Staggered magazines; 5- and 20-round capacity
Sights 6x scope
Weight: with empty magazine 14.11 pounds (6.41 kg)
Barrel length 23.62 inches (600mm)
Overall length 45.87 inches (1,165mm)
Width 2.56 inches (65mm)
Height 10.23 inches (259.8mm)