Speaking of futuristic weapons... check this out
www.metalstorm.com
• 100% electronic, no mechanical moving parts
• unique 100% solid state system
• electronically variable rate of fire confirmed to one million rounds per minute
• application across a broad range of defence and commercial end uses
ROF 1 milion rounds/ minute <---- OMFG!!!
Don't think it fits the catagory of an assault rifle though :)