This is a very odd entry b/c the "Carbine" Williams designer of the M-1 rifle developed in the early 1950s a belt-fed .22LR caliber machinegun called the Model 7 which was a crude alpha version of a more advanced design to come later. Williams worked on several novel features of the gun, but the US Army was skeptical and Williams would not let them examine the internal workings of the gun- so no orders. Williams let them test the MG which shot at 2700 rpm!!! It took belts of 250, 500, and 1000 rounds, but was impractical for a soldier to carry all that weight although the gun weighed just 5 lbs as it was made entirely of aluminium!!! Williams died and then left the patent and prototypes to LE Lisk, so the designation changed to LEL-1. This was a modifieid version that looked like something out of "Flash Gordon"!!! It had a novel free-floating receiver, knob auto-selector for fire control, weighed the same 5 lbs, and ejected the casings downwards vertically. The US Army still had an interest, but Lisk also did not trust anyone and would not allow internal inspection or any form of disassembly at all!!! So, no orders and the guns are still locked away in secret. Basically a futuristic 1950s-70s design that can still crank out 2700-3000 rpm!!! Lisk will probably take the patent and guns to his grave rather then let anyone inspect the guns!!! Photo below...

http://i.imgur.com/pCjcx.jpg