It's great to have a friend with his own range and the papers to build full-auto firearms!
This video is of him shooting a Glock 17 modified to full auto (no selector switch), one burst of 33 rounds. This guy is strong and as you can see is well braced up to hang on for the entire mag, which is pretty tough to do. When I shot it, it took me 5 bursts and I still hit the ceiling on one...my video looked pretty clumsy.
The only use I can see for such a piece is for covering fire, since it's nearly impossible to shoot with any precision or control.