PLR-16
Kel-Tec has developed a 300 Blackout version of the SU-16. They'll be showing it at the 2012 SHOT Show and almost certainly selling it in 2012. It was an easy conversion, once they decided to do it.
http://www.thektog.org/forum/showthread.php?t=245004
So, my question, as I posed in the above...