A select-fire assault rifle can fire thousands of rounds per minute but only to the capacity of the magazine.
The MAC-11 is exceptional at 1200 RPM, and is exceptionally fin to shoot, which I can personally attest. http://www.youtube.com/watch?v=zZnpokRP_bU
The Nazi MG42 belt fed was very fast at 1200-1500, too.
To get into the “thousands” you’re in Gatling gun territory.
Sorry about that. I meant hundreds but typed thousands. Need more coffee.