slide fire stock on AR?

[Roverron]

Saw this video on using a slide fire stock. To me it appears to make the gun a close to full auto, without NFA regs.
http://youtu.be/dvLt8-Wf7r0

[Bello]

It's like bump firing without the ghettoness

[titanse05]

For a range toy, I could see the fun value in the slide fire stock. However, I would never put one on either of my ARs. Full auto bursts are more difficult to keep on target and are a excellent way to waste ammo. At todays rising prices I'm looking to put every round on target.