Colt quit making some of thier different calibur uppers. But, RRA still can do 9mm uppers and conversion set ups. I love the 9mm AR. It is a real fun one. Here is a YOUTUBE on one being played with.
http://www.youtube.com/watch?v=VLCku... 9mm - YouTube
I took my new 9mm, AR out today after fixing the extractor problem it had. Put 200 rounds through it with NO malfunctions.
That little EOTECH scope was spot dead on out of the box.
Went through several UZI mags I machined last month to work in this system.
This is also one of the ones I did an 80% lower on. All of the 9mm parts work just great in it.