OK, I'm throwing this out there... the Benelli M4 Shotgun has one of the fastest semi-auto actions out there, bar none. Here's a demonstration.
How about this...eight shots in just a smidge over 1 second.
Shotgun in the video has had no modifications to its trigger or action, in any way, just a full length mag tube installed.
Find something faster in a semi-auto?
Post it up here, but remember...eight shots in 1.2 seconds...has to be that fast or faster.