I agree this looks fun as hell. The only problem is affording all that "fun"!
A mag of 30 rounds for an AR/AK costs anywhere from $7.00 and up. You can go thru that in less than 2 seconds. Fun = money. I still want one! A registered machine gun is $10,000 or more depending on the type. Points for the "flash enhancer".
This Slide Fire stock is available for AR15 and AK47 platforms and retails for about $350.00.
Read more here.