Head down products will be releasing a take down AR that keeps the upper and lower receivers together. Skip to 9:00 to see the takedown barrel assembly.
I really like this. Of course, I have a thing for takedown rifles and even though the AR can be stored in discreet cases by separating the upper and lower, I kinda dig this new method. Hopefully we can still get things like this in 2013. I wonder what the price point on the parts for this is going to be. I might make a carbine upper based on this design. Cheers.