Thanks for the clarification. Now I get it.Sorry, I meant, why am I just now learning about this particular gun.
Lots of people don't seem to know they exist. Depending on which reference you read or listen to, somewhere between 200 and 3000 were imported before the ban so they are kinda rare. (Wikipedia says "less than 2000", which isn't terribly precise.)
Side note: most sources say 30 round magazines fit. I'm not so sure. I've seen them inserted and locked in place. However, I've tried it and the magazine floorplate hits the bottom of the pistol grip. There's too much jiggling and forcing involved for me to consider insertion to be easy enough to be fun. I just have a stack of 20-rounders.